function returning String

This is a discussion on function returning String within the C Programming forums, part of the General Programming Boards category; I'm writing a function that will be called everytime the program ask for the user to input something. Code: int ...

  1. #1
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    function returning String

    I'm writing a function that will be called everytime the program ask for the user to input something.
    Code:
    int main(voidz)
    {
        char integer[INT_SIZE+EXTRA_SPACES];
        int number;
        printf("Enter a number.");
        *integer=getInput(INT_SIZE);
        number=atoi(integer);
        printf("%i",&integer);
    
    
    }
    
    
    
    
    
    
    void readRestOfLine()
    {
       int c;
    
    
       /* Read until the end of the line or end-of-file. */
       while ((c = fgetc(stdin)) != '\n' && c != EOF);
    
    
       /* Clear the error and end-of-file flags. */
       clearerr(stdin);
    }
    
    
    char* getInput(int size)
    {
        char input[size+EXTRA_SPACES];
        fgets(input,size+EXTRA_SPACES,stdin);
        if (input[strlen(input) - 1] != '\n')
        {
            /* String was too long. Reject string and flush input buffer. */
            printf("Input was too long.\n");
            readRestOfLine();
        }
        else
        {
             input[strlen(input) - 1] = '\0';
             return input;
        }
    }
    My problem is,it's not printing the number entered,but the memory location(i think).And also,when a invalid(over-length) input,it still print out the memory location.
    Thanks.

  2. #2
    Registered User claudiu's Avatar
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    I don't know who taught you to read from a file like that but it's just mental.

    On another note "integer" is a char array and you are printing its address. Google how to printf a char array in C.

    Also, int main(VOIDZ????) Hahaha.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  3. #3
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    oops,sorry about the error up there.
    Code:
    int main(void)
    {
        char integer[INT_SIZE+EXTRA_SPACES];
        int number;
        printf("Enter a number.");
        *integer=getInput(INT_SIZE);
        number=atoi((void*)integer);
        printf("%s",integer);
        printf("%i",number);
    
    
    }
    why it's not working for the both printf?

  4. #4
    Registered User claudiu's Avatar
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    number=atoi((void*)integer);

    What the hell are you trying to achieve here?

    Also, is integer correctly terminated?
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  5. #5
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    231
    You should pass char-Array to your function, you should never return an lokal automatic variable to the calling context, try:
    Code:
    int main(void)
    {
        char integer[INT_SIZE+EXTRA_SPACES];
        int number;
        printf("Enter a number.");
        getInput(INT_SIZE+EXTRA_SPACES,integer);
        number=atoi(integer);
        printf("%i",number);
    }
    
    void readRestOfLine()
    {
       int c;
    
    
       /* Read until the end of the line or end-of-file. */
       while ((c = fgetc(stdin)) != '\n' && c != EOF);
    
    
       /* Clear the error and end-of-file flags. */
       clearerr(stdin);
    }
    
    
    char* getInput(int size,char *input)
    {
        fgets(input,size,stdin);
        if (input[strlen(input) - 1] != '\n')
        {
            /* String was too long. Reject string and flush input buffer. */
            printf("Input was too long.\n");
            readRestOfLine();
        }
        else
        {
             input[strlen(input) - 1] = '\0';
             return input;
        }
    }

  6. #6
    spurious conceit MK27's Avatar
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    You should be compiling with warnings enabled. This:

    Code:
       char input[size+EXTRA_SPACES];
    is a local variable. You can't return those because they go out of scope when the function ends. Ie, they don't really exist. They may seem to exist, but they are prone to getting overwritten, in whole or in part, by something else (if you used the compiler warnings, you would know this).
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  7. #7
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    thanks~it's working now....^^

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