fgets not truncating text

Hello,

My program actually works but has bugs in it and I don't know why the bugs are showing up.

Background
I am teaching myself how to program in C. I have been studying this for a while in my spare time and have written a program to test out what what I can remember from the skills I have learned. This isn't for anything other than my own self satisfaction and testing my skills thus far.

I am programming in a Linux environment and am a beginner with gdb, linux, C and the GCC compiler. I cannot get gdb to get past any fgets functions I have in the program. It hangs every time it gets to fgets so gdb is pretty much useless to me in trying to figure this out. Even when I try to type something in and hit enter it doesn't work. I even push ENTER 500 times (dramatization but not far off) and that finally gets past it but then proceeds too far in to the program even using next function and I have tried to manually set the variable by using set x="Whatever" to no avail.

Issue
When running the program if you type in text longer than what fgets is expecting instead of dropping the excess text like I have seen it do before, the excess text is getting copied over to the next question and causing the next questions to be answered automatically by the excess text.

Example
What is the 1st employees first name:
Correct Answer: Kammi
Buggy Answer: Kammiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii i

Result
The correct answer is perfect. It will cause the next question to come up. The buggy answer will cause the unexpected result of the immediate question being answered with kammiiiiiiiiiiiiiii (19 characters because fgets is set to take in 20 characters including the NUL terminator '\0') however then it answers the next question which ends up as "What is Kammiiiiiiiiiiiiiii's last name? " as "iiiiiiiiiiiiiiiii" and continues this behavior until all of the iiiiiiii's have been used up.

Attempts

• I have tried to use fflush(stdout) after the question to no avail.
• I have attempted to look at the length of the string and clear out the string if it is over what is expected. If I use a printf("Length of String: %d",strlen(storage)); it prints out the string length I was expecting.
• I remove the new line that fgets inserts automatically and replace it with a 0 already (if it finds one), I have attempted to set it to a NUL terminator instead.

Question
I have no idea what is causing this issue and need some help telling me what's wrong and how to fix it. Can someone please look over the code and tell me what's wrong with it?

Code
CodePaste.NET - Working code for using structures, arrays and pointers all together. - Every line has been commented.

GCC Compiling Command
gcc -ggdb -std=c99 -Wall -Werror ptr-strct.c -lcrypt -lcs50 -lm -o ptr-strct

Other Notes
There may be other commands not recognized by some people such as -lcs50 and also questions as to why I am using other settings such as -std=c99. This is because I am going through the Harvard classes and am using the CS50 appliance provided by Harvard.

The '\0' character is not being put at the end of the string.

It is automatically placed in there when I use fgets. I shouldn't need to add it. Is that not correct? I have actually also tried to update the removenew line to replace the \n with '\0' instead and that didn't fix it.

Give your string an extra character and initialise this last character to '\0'

It doesn't work. Here is what I did.
I updated the MAXNAME macro from 20 to 21.

I changed the removenewline function from changing the '\n' to 0 to change it to '\0'. This will ensure that there will indeed be a NUL terminator in there. I have done this before.

The result:
What is the 1st employees first name? Kammiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
What is Kammiiiiiiiiiiiiiiii's last name? How old is Kammiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiii? What is Kammiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiii's hourly wage? $What is the date of hire for Kammiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiii (ie. 04-20-1975)? When was the last pay raise date for Kammiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiii (ie. 04-20-1975)? What is the home phone for Kammiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiii (ie. 555-555-5555)?

Just update the declaration to MAXNAME + 1, not the value of MAXNAME

Code:

---

char *storage; // Create a storage container to store the answer from the user in fgets.
storage=malloc(sizeof(company)); // Allocate memory for the pointer just created with malloc

...


printf(" employees first name? "); // End the question to the user and wait for input with fgets.
fgets(storage->fname,MAXNAME,stdin); // Store the retreived information into the structure.
storage=removenewline(storage->fname); // Remove the new line added by fgets so we can print on the same line.

---

I have tried this is multiple places. In the struct I tried fname[MAXNAME+1]. This did not work. I tried in in the fgets function: fgets(storage,MAXNAME+1,stdin); and that didn't work.

Now realize that I have this function that removes the newline that fgets automatically adds to the string. It looks for '/n' and replaces it with '/0'. This means that a NUL terminator is in the string. Now the code above will replace it with only 0 because I have already attempted to replace it with a '\0' and that didn't work. I guess the point I am trying to get to is that I have ensured that there is indeed a NUL terminator at the end of the string and that is not causing the issue.

The issue even happens on the float's and integers. If you include 20.77777777777777777777777777777777777777777777777 7777777777777777777777777 it does the same thing. I accept it as a string and then convert it using the atoi and atof functions.

Wayne

Quote:

---

Originally Posted by Click_here

Code:

---

char *storage; // Create a storage container to store the answer from the user in fgets.
storage=malloc(sizeof(company)); // Allocate memory for the pointer just created with malloc

...


printf(" employees first name? "); // End the question to the user and wait for input with fgets.
fgets(storage->fname,MAXNAME,stdin); // Store the retreived information into the structure.
storage=removenewline(storage->fname); // Remove the new line added by fgets so we can print on the same line.

---

---

I used to have that in there but I received the following errors which is why I had to go to the strcpy function.

ptr-strct.c:75:22: error: request for member 'fname' in something not a structure or union
ptr-strct.c:76:38: error: request for member 'fname' in something not a structure or union

Code:

---

char *storage; // Create a storage container to store the answer from the user in fgets.

//Should be

company *storage; // Create a storage container to store the answer from the user in fgets.

---

Quote:

---

Originally Posted by Click_here

Code:

---

char *storage; // Create a storage container to store the answer from the user in fgets.

//Should be

company *storage; // Create a storage container to store the answer from the user in fgets.

---

---

When I do that I get the following errors:

jharvard@appliance (~/Desktop/CS50/source code files): make ptr-strct
gcc -ggdb -std=c99 -Wall -Werror ptr-strct.c -lcrypt -lcs50 -lm -o ptr-strct
ptr-strct.c: In function 'storedata':
ptr-strct.c:75:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:76:9: error: passing argument 1 of 'removenewline' from incompatible pointer type [-Werror]
ptr-strct.c:29:7: note: expected 'char *' but argument is of type 'struct company *'
ptr-strct.c:76:16: error: assignment from incompatible pointer type [-Werror]
ptr-strct.c:77:9: error: passing argument 2 of 'strcpy' from incompatible pointer type [-Werror]
/usr/include/string.h:128:14: note: expected 'const char * restrict' but argument is of type 'struct company *'
ptr-strct.c:81:9: error: passing argument 1 of 'strlen' from incompatible pointer type [-Werror]
/usr/include/string.h:399:15: note: expected 'const char *' but argument is of type 'struct company *'
ptr-strct.c:82:29: error: invalid operands to binary == (have 'company' and 'int')
ptr-strct.c:87:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:88:9: error: passing argument 1 of 'removenewline' from incompatible pointer type [-Werror]
ptr-strct.c:29:7: note: expected 'char *' but argument is of type 'struct company *'
ptr-strct.c:88:16: error: assignment from incompatible pointer type [-Werror]
ptr-strct.c:89:9: error: passing argument 2 of 'strcpy' from incompatible pointer type [-Werror]
/usr/include/string.h:128:14: note: expected 'const char * restrict' but argument is of type 'struct company *'
ptr-strct.c:98:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:99:9: error: passing argument 1 of 'atoi' from incompatible pointer type [-Werror]
/usr/include/stdlib.h:148:12: note: expected 'const char *' but argument is of type 'struct company *'
ptr-strct.c:103:9: error: passing argument 1 of 'strlen' from incompatible pointer type [-Werror]
/usr/include/string.h:399:15: note: expected 'const char *' but argument is of type 'struct company *'
ptr-strct.c:105:29: error: invalid operands to binary == (have 'company' and 'int')
ptr-strct.c:110:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:113:9: error: passing argument 1 of 'strlen' from incompatible pointer type [-Werror]
/usr/include/string.h:399:15: note: expected 'const char *' but argument is of type 'struct company *'
ptr-strct.c:118:13: error: passing argument 1 of 'removenewline' from incompatible pointer type [-Werror]
ptr-strct.c:29:7: note: expected 'char *' but argument is of type 'struct company *'
ptr-strct.c:118:20: error: assignment from incompatible pointer type [-Werror]
ptr-strct.c:119:13: error: passing argument 1 of 'atof' from incompatible pointer type [-Werror]
/usr/include/stdlib.h:145:15: note: expected 'const char *' but argument is of type 'struct company *'
ptr-strct.c:124:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:125:9: error: passing argument 1 of 'removenewline' from incompatible pointer type [-Werror]
ptr-strct.c:29:7: note: expected 'char *' but argument is of type 'struct company *'
ptr-strct.c:125:16: error: assignment from incompatible pointer type [-Werror]
ptr-strct.c:126:9: error: passing argument 2 of 'strcpy' from incompatible pointer type [-Werror]
/usr/include/string.h:128:14: note: expected 'const char * restrict' but argument is of type 'struct company *'
ptr-strct.c:129:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:130:9: error: passing argument 1 of 'removenewline' from incompatible pointer type [-Werror]
ptr-strct.c:29:7: note: expected 'char *' but argument is of type 'struct company *'
ptr-strct.c:130:16: error: assignment from incompatible pointer type [-Werror]
ptr-strct.c:131:9: error: passing argument 2 of 'strcpy' from incompatible pointer type [-Werror]
/usr/include/string.h:128:14: note: expected 'const char * restrict' but argument is of type 'struct company *'
ptr-strct.c:134:9: error: passing argument 1 of 'fgets' from incompatible pointer type [-Werror]
/usr/include/stdio.h:626:14: note: expected 'char * restrict' but argument is of type 'struct company *'
ptr-strct.c:135:9: error: passing argument 1 of 'removenewline' from incompatible pointer type [-Werror]
ptr-strct.c:29:7: note: expected 'char *' but argument is of type 'struct company *'
ptr-strct.c:135:16: error: assignment from incompatible pointer type [-Werror]
ptr-strct.c:136:9: error: passing argument 2 of 'strcpy' from incompatible pointer type [-Werror]
/usr/include/string.h:128:14: note: expected 'const char * restrict' but argument is of type 'struct company *'
cc1: all warnings being treated as errors
make: *** [ptr-strct] Error 1

You have a choice -

Code:

---

char *storage; // Create a storage container to store the answer from the user in fgets.
storage=malloc(sizeof(MAXNAME)); // Allocate memory for the pointer just created with malloc

// And have a string "storage" of size MAXNAME, or

company *storage; // Create a storage container to store the answer from the user in fgets.
storage=malloc(sizeof(company)); // Allocate memory for the pointer just created with malloc

// And go through making sure that you are writing to the correct members in the structure.

---

fgets() does truncates input. Try to add a full row of text, and see for yourself.

Code:

---

#include <stdio.h>
#include <string.h>

#define SIZE 50

int main(void) {
  char name[SIZE];
  char *pch;
  int len;

  fgets(name, sizeof(name), stdin);
 
  len=strlen(name);
  pch=&name[len-1];
  if(*pch=='\n')
      *pch='\0';
  printf("name: %s has %d chars in it\n",name,strlen(name));

  return 0;
}

---

I originally had the MAXNAME in my code for the storage container however I through that perhaps since I was sending the stuff to a struct I need to allocate enough memory to store everything in the struct so I changed it to company.

I actually has char* storage=malloc((MAXNAME*2)+2) just like char* fullname.

I will try changing it back right now and report back.

Wayne

refer C FAQ

Question 12.26a

Question 12.26b

Quote:

---

Originally Posted by Adak

fgets() does truncates input. Try to add a full row of text, and see for yourself.

Code:

---

#include <stdio.h>
#include <string.h>

#define SIZE 50

int main(void) {
  char name[SIZE];
  char *pch;
  int len;

  fgets(name, sizeof(name), stdin);
 
  len=strlen(name);
  pch=&name[len-1];
  if(*pch=='\n')
      *pch='\0';
  printf("name: %s has %d chars in it\n",name,strlen(name));

  return 0;
}

---

---

The title might be off because as a beginner that is what it appeared to me was happening. However the issue that is happening is still present.

Quote:

---

char *storage; // Create a storage container to store the answer from the user in fgets.storage=malloc(sizeof(MAXNAME)); // Allocate memory for the pointer just created with malloc// And have a string "storage" of size MAXNAME, orcompany *storage; // Create a storage container to store the answer from the user in fgets.storage=malloc(sizeof(company)); // Allocate memory for the pointer just created with malloc// And go through making sure that you are writing to the correct members in the structure.

---

I changed the malloc back to MAXNAME and that didn't help out at all. The below is still the same result. My understanding is the malloc simply allocates memory on the heap to be able to use so it shouldn't matter other than the amount of memory I am allocating whether or not I use MAXNAME (which is equal to 20) or company (which is equal to 112). As long as there is enough memory to hold the requests, isn't that correct?

Result
What is the 1st employees first name? Kammiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
What is Kammiiiiiiiiiiiiiii's last name? How old is Kammiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiii? What is iii's hourly wage? $What is the date of hire for iii (ie. 04-20-1975)? When was the last pay raise date for iii (ie. 04-20-1975)? What is the home phone for iii (ie. 555-555-5555)?

Quote:

---

Originally Posted by fnoyan

refer C FAQ

Question 12.26a

Question 12.26b

---

I have read 12.26a and already tried fflush(stdout) without success.
I had not read 12.26b and that was pretty interesting to know. Is that trying to tell me that there is nothing standardized that I can do in order to get rid of additional characters? Really?

Quote:

---

Is that trying to tell me that there is nothing standardized that I can do in order to get rid of additional characters? Really?

---

No, it said

Quote:

---

Alternatively, you can consume the rest of a partially-read line with a simple code fragment like


while((c = getchar()) != '\n' && c != EOF)
/* discard */ ;

---

Okay,

I will try that right now. Although I am not really sure how to implement that so I will have to figure out what this actually means. It looks like it has EOF which I understand to be End of File which would indicate that it is talking about opening an actual file which is not the case here, is that correct?

Wayne

Quote:

---

Originally Posted by scrfix

I had not read 12.26b and that was pretty interesting to know. Is that trying to tell me that there is nothing standardized that I can do in order to get rid of additional characters? Really?

---

yes... so, you may want to write your own function.

Have you tried compiling the same code under Win32 (not with MinGW or Cygwin)? (i.e with a completely different fflush() implementation)

Please also refer (or from command line "man 3 fflush")
http://manpages.ubuntu.com/manpages/.../fflush.3.html

And, is there a particular reason why you do not use scanf()?

Quote:

---

Originally Posted by fnoyan

yes... so, you may want to write your own function.

Have you tried compiling the same code under Win32 (not with MinGW or Cygwin)? (i.e with a completely different fflush() implementation)

---

I have not tried compiling it with another OS other than GCC in the Linux environment. I kind of wanted to get it working first in the linux environment prior to compiling it in another environment.

Well, definitely the flushing does not work for you here. So, you may;

1 ) write your own function to read from input
2 ) Use scanf()

I'd vote for option 2

Quote:

---

Originally Posted by fnoyan

Well, definitely the flushing does not work for you here. So, you may;

1 ) write your own function to read from input
2 ) Use scanf()

I'd vote for option 2

---

So what you are telling me is that fgets is not the correct function to use here because people can obviously type more than what fgets expects and it doesn't just drop the excess text. I was told to use fgets when accepting string input because it checks the length of the string. I should not be using that? I should be using scanf instead? Isn't there a length buffer overflow that can happen with using scanf?

I will try to change the code from fgets to scanf's to see if that prevents the issue.

Wayne

Have a look at this example:

Code:

---

int main(void)
{
    char *fname;
    int read_ok;


    fname = malloc(MAXNAME * sizeof(*fname));


    do
    {
        char *s;

        printf("Enter Name:");
        fflush(stdout);


        fgets(fname, MAXNAME, stdin);
        if ((s=strstr(fname, "\n")) != NULL)
        {
            *s = '\0';
            read_ok = 1;
        }
        else
        {
            int c;
            while((c = getchar()) != '\n' && c != EOF) continue;


            fprintf(stderr, "Problem with string size\n");
            read_ok = 0;
        }
    } while (read_ok == 0);


    printf("Name is %s\n", fname);


    free(fname);


    return 0;
}

---

[edit]
Note that using scanf for strings can be dangerous if you don't restrict the input - You risk having an overflow.

The easiest way of managing input is using fgets, like the example I have given above.
[/edit]

Quote:

---

Originally Posted by scrfix

So what you are telling me is that fgets is not the correct function to use here ....

---

No fgets() is a better choice actually, obviously you can implement scanf() functionalty as a combination of fgets() + sscanf() functions.

You can truncate input with scanf(), fscanf() or sscanf(), and we know that fgets() can always truncate input to the size you specify.

C has nothing in the standard, to stop the user from pressing keys on his keyboard, and having them echoed up to the screen. (There is a small char buffer that handles that).

Some of that is a little over my head but I will study the code and then try to implement it in my code. Thanks. I will try to get back to you with what my results are but that probably won't be tonight unless I get it completed tonight. :D

From what I can tell each line does the following. The only thing I have not seen before is the continue keyword phrase. I am not sure what function that actually serves.

The conditional within the do while loop looks like it will never hit the else condition because it looks for the \n using strstr and then sets read_ok=1; Since we are using fgets and it adds the \n it will find it, set read_ok=1 and proceed. It will skip past the else since we have already determined. It will get to the while and see that read_ok is not set to 0 and it will exit out of the do while loop. Am I wrong about that?

Code:

---

int main(void)
{
  char *fname;                  // Create a pointer of type char.
  int read_ok;                  // Create a read_ok variable of type int


  fname = malloc(MAXNAME * sizeof(*fname)); // Malloc out MAXNAME which is 20 bytes * the size of a pointer which is 4 bytes so this should malloc 80 bytes of memory on the heap.


  do                            // This will run a minimal of once even if read_ok does not equal 0.
  {
    char *s;                    // Create a pointer that will point to a type char.

    printf("Enter Name:");      // Print out sentence asking user for input.
    fflush(stdout);            // Flush out the standard output.


    fgets(fname, MAXNAME, stdin); // Wait for input from the user.  Store that input into the malloc'ed space that fname is pointing to.
    if ((s = strstr(fname, "\n")) != NULL)  // Look for the first occurrence of \n and if we find one then proceed.
    {
      *s = '\0';                // Replace that occurrence with a NUL terminator.
      read_ok = 1;              // Set read_ok to 1.  This means that the do while loop will end.
    } else                      // There was no new line found. However it doesn't appear that this will ever be reached.
    {
      int c;                    // Create a variable of type int.
      while ((c = getchar()) != '\n' && c != EOF)
        continue;              // I believe this is supposed to be looking at each character while it gets typed however I believe fgets will prevent this from ever being used.  I don't know what continue does.


      fprintf(stderr, "Problem with string size\n");  // I have never used fprintf before so I am not sure what this does other than prints out the error code and text.
      read_ok = 0;
    }
  } while (read_ok == 0);      // Only do this while the int read_ok is equal to 0.


  printf("Name is %s\n", fname);  // Print out the text stored in the pointer.


  free(fname);                  // Free the memory malloc'ed.


  return 0;                    // Successful completion
}

---

Quote:

---

C has nothing in the standard, to stop the user from pressing keys on his keyboard, and having them echoed up to the screen. (There is a small char buffer that handles that)

---

I know they don't have anything to stop people from pressing keys on the keyboard or it repeating on the screen. I was looking for something to stop the rest of the excess text from going in to my next answers after enter is pushed.

Quote:

---

// Create a variable of type int.
int c;

// I believe this is supposed to be looking at each character while it
// gets typed however I believe fgets will prevent this from ever being
// used. I don't know what continue does.

while((c = getchar()) != '\n' && c != EOF) continue;

---

I think that you can see that it keeps pulling stuff off stdin until either a new line is found, or the EOF.

"continue" is used in loops to say "start the loop again". It is not needed: However, I've put it here so that this "while" can be easily told apart from the end of a do/while loop when looking at the code.

If you wanted my advice on how to implement this into your code, turn this into a function like this:

Code:

---

void get_user_input (char *prompt, char *input_string, size_t input_string_size);


int main(void)
{
    char *fname;


    fname = malloc(MAXNAME * sizeof(*fname));


    get_user_input ("Enter first name", fname, MAXNAME);


    printf("Name is %s\n", fname);


    free(fname);


    return EXIT_SUCCESS;
}


void get_user_input (char *prompt, char *input_string, size_t input_string_size)
{
    int read_ok;


    do
    {
        char *s;


        printf("%s: ", prompt);
        fflush(stdout);


        fgets(input_string, input_string_size, stdin);
       
        if ((s=strstr(input_string, "\n")) != NULL)
        {
            *s = '\0';
            read_ok = 1;
           
        }
        else
        {
            int c;
           
            while((c = getchar()) != '\n' && c != EOF)
            {
                continue;
               
            }


            fprintf(stderr, "Problem with string size\n");
            read_ok = 0;
           
        }


    }
    while (read_ok == 0);


}

---

There is one last thing to worry about - That's the return value from fgets -> If this is NULL, there is a big problem. I've implemented this with a return value. [edit] It would also be worth mentioning the return value from malloc should not be NULL [/edit]

If you want to test if it is working, change stdin to stdout

Code:

---

char *get_user_input (char *prompt, char *input_string, size_t input_string_size);


int main(void)
{
    char *fname;


    if ((fname = malloc(MAXNAME * sizeof(*fname))) == NULL)
    {
        fprintf(stderr, "-ERROR-\nAllocation Failure\n");
        return EXIT_FAILURE;
    }


    if (get_user_input ("Enter first name", fname, MAXNAME) != NULL)
    {
        printf("Name is %s\n", fname);
    }
    else
    {
        fprintf(stderr, "-ERROR-\nProblem with reading string\n");

        return EXIT_FAILURE;
    }


    free(fname);


    return EXIT_SUCCESS;
}


char *get_user_input (char *prompt, char *input_string, size_t input_string_size)
{
    int read_ok;
    char *return_val;


    do
    {
        char *s;


        printf("%s: ", prompt);
        fflush(stdout);




        if ((return_val = fgets(input_string, input_string_size, stdin)) == NULL)
        {
            break;
        }


        if ((s=strstr(input_string, "\n")) != NULL)
        {
            *s = '\0';
            read_ok = 1;


        }
        else
        {
            int c;


            while((c = getchar()) != '\n' && c != EOF)
            {
                continue;


            }


            fprintf(stderr, "Problem with string size\n");
            read_ok = 0;


        }


    }
    while (read_ok == 0);


    return return_val;
}

---

Personally, I would initialise read_ok to 0 and return_val to NULL, even though they are correctly given initial values within the loop body. prompt should be a const char*. I would prefer strchr to strstr here. (Nominal Animal's strcspn idea does not fit quite as well into your current logic, methinks.) Oh, and all those extra blank lines make me :(

Quote:

---

Originally Posted by laserlight

Personally, I would initialise read_ok to 0 and return_val to NULL, even though they are correctly given initial values within the loop body. prompt should be a const char*. I would prefer strchr to strstr here. (Nominal Animal's strcspn idea does not fit quite as well into your current logic, methinks.) Oh, and all those extra blank lines make me :(

---

Initialising is always a good idea.

strchr is a better idea

const char * is a better idea

I don't know where you are seeing Nominal Animal's suggestion, though...

The extra blank lines are from a A-Style indentation program -> I'm fairly sure that I'm not a fan of it either...

Here is one that the whole family can enjoy...

Code:

---

char *get_user_input (const char *prompt, char *input_string, size_t input_string_size);


int main(void)
{
    char *fname;


    if ((fname = malloc(MAXNAME * sizeof(*fname))) == NULL)
    {
        fprintf(stderr, "-ERROR-\nAllocation Failure\n");
        return EXIT_FAILURE;
    }


    if (get_user_input ("Enter first name", fname, MAXNAME) != NULL)
    {
        printf("Name is %s\n", fname);
    }
    else
    {
        fprintf(stderr, "-ERROR-\nProblem with reading string\n");
        return EXIT_FAILURE;
    }


    free(fname);


    return EXIT_SUCCESS;
}


char *get_user_input (const char *prompt, char *input_string, size_t input_string_size)
{
    int read_ok = 0;
    char *return_val = NULL;


    if (prompt == NULL || input_string == NULL || input_string_size <= 0)
    {
        return NULL;
    }


    do
    {
        char *s;


        printf("%s: ", prompt);
        fflush(stdout);


        if ((return_val = fgets(input_string, input_string_size, stdin)) == NULL)
        {
            break;
        }


        if ((s = strchr(input_string, '\n')) != NULL)
        {
            *s = '\0';
            read_ok = 1;
        }
        else
        {
            int c;
            while((c = getchar()) != '\n' && c != EOF)
            {
                continue;
            }


            fprintf(stderr, "Problem with string size\n");
            read_ok = 0;
        }
    }
    while (read_ok == 0);


    return return_val;
}

---

Quote:

---

Originally Posted by Click_here

I don't know where you are seeing Nominal Animal's suggestion, though...

---

In a different thread, which you may have seen since you've been around long enough.

Quote:

---

Originally Posted by laserlight

In a different thread, which you may have seen since you've been around long enough.

---

I think I found what you were talking about here - http://cboard.cprogramming.com/c-pro...-new-line.html - I remember it now; how can I forget this classic by soma

Quote:

---

[Edit]
*sigh*


Removed the wrong portion of the post.


I have no idea what was written here. Sorry.
[/Edit]

---

Nominal Animal's code is a very neat way of removing new line characters. However, you are right in saying that it would not fit my example, as the problem I tried to solve is whether a new line has been included in the input from fgets