Thread: Why my code crashes

Hi, I need the user to enter coordinates x,y . The x needs to go in front of the number like so : x8.2 . My code works , but it accepts x8.2 just the same as 8.2x. This is not allowed to happen ie . it must reject the point if it sees the x at the end . Here is what I came up with :

Code:

#include <stdio.h>
int main(void)

{

FILE * output = stdout;
FILE * input = stdin;

char stringValue[8];
float value;
fscanf(input, "%s", stringValue); 

// check last character
if (stringValue[ strlen( stringValue ) - 1] == 'x')

{
	fprintf(output,"You have entered incorrect value - put the x at the front !");// wrong value
	return 0;
}

else

{
	fscanf(input, "%f", value);
	fprintf(output,"The program will continue");
}

}

I run that , it works for any number with x at the end , it says incorrect put at x at front , but if a correct number is putin, it will crash ? If Im not doing this correctly can you show me the right way ?
Thank you

Im an idiot it crashes because I forgot the &value , instead of just value .

Since you're telling fgets() to read at most 10 characters (including the final null character), you need to allocate at least that many, so you should use

Code:

char guess[10];

Ok I am now using

Code:

char guess[10]

However no matter what I put in it says Try again . This includes if i enter EDDIE and "EDDIE". Any idea why it's doing this ? ( Ichanged the code posted before to show what I did )

I have also tried changing the code to this :

Code:

int name[] = {"EDDIE"};
char guess[10];
int correct = 0;

But I highly doubt that the second method can work .
Thanks for your time

Originally Posted by ICool

However no matter what I put in it says Try again . This includes if i enter EDDIE and "EDDIE". Any idea why it's doing this ?

fgets leaves the terminating '\n' at the end of the returned string.
one way to get rid of that is

Code:

        char *p;
        p = strchr(guess, '\n');
        if ( p ) 
            *p = 0;

Kurt

As said before, it is the '\n' char which is playing your problem. Remove the \n char and replace that with the '\0' char. Beforem you compare the two string.

That should work. And work along your code indendation.

ssharish2005

Originally Posted by ZuK

fgets leaves the terminating '\n' at the end of the returned string.
one way to get rid of that is

Code:

        char *p;
        p = strchr(guess, '\n');
        if ( p ) 
            *p = 0;

Kurt

Can you please clarify what you mean . How would I implement the above code . This compiles but crashes :

Code:

printf("Enter a name in uppercase: ");
char *p;
p = strchr(guess, '\n');
if ( p ) 
*p = 0;

while(!correct)

Code:

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

int main()  {
    char *name = "EDDIE";
    char guess[10];
    int correct = 0;
    char * p;

    printf("Enter a name in uppercase: ");

    while(!correct) {
        fgets(guess ,10, stdin);
        p = strchr(guess, '\n');
        if ( p ) 
            *p = 0;
            
	if(strcmp(name, guess)==0) {
	    printf("Correct!\n");
            correct = 1;
        }	  
        else  {
            printf("Try again: ");
        }
    }
}

kurt

Thank you so much . That works perfectly

Is this how I would do the same but for more than 1 name ?

Code:

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

int main() {
int name[] = {"EDDIE","BEN","DAVE"};

char guess[10];
int correct = 0;
char * p;

printf("Enter a name in uppercase: ");

while(!correct) {
fgets(guess ,10, stdin);
p = strchr(guess, '\n');
if ( p ) 
*p = 0;

if(strcmp(name, guess)==0) {
printf("Correct!\n");
correct = 1;
} 
else {
printf("Try again: ");
}
}
}

does it compile ?

Kurt