Just started. nedd help

[VBakias]

Hi,
This is my code

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

int sig(char [], char []);


void main()
{
  char a[30];
  char b[30];
  
  scanf("%s", &a);
  scanf("%s", &b);

  printf("%d\n",sig(a,b));
}

int sig(char a[], char b[])
{
  int i;
  for (i=0; strlen(a); i++)
  {
    if (a[i] != b[i])
      return(0);
  }
  return(1);
}

This is supposed to tahe two strings in a char array and compare them cell by cell. If one cell is not equal to the other at the second array (a != b) the function should return 0. If the condition in the if statement never gonna be true, as the for loop finishes it will return1.

It always return 0.

? tnx

 

[Salem]

> void main()
main returns an int

> for (i=0; strlen(a); i++)
You need an explicit comparison. You've written
for (i=0; strlen(a) != 0 ; i++)

> scanf("%s", &a);
Drop the & here - a is an array
scanf("%s", a);


--

 

[uolj]

In the future, you should probably ask questions about C code in a C forum. This time, your problem looks to be a simple error in the control for your for loop. The way the code is currently written, you are looping while strlen(a) is true (i.e. non-zero), which will always be the case unless a is empty. So the loop continues forever, or until the inner if statement leads to a return 0.

What you probably wanted to do was loop while i is less than strlen(a). So to fix the problem just modify the for loop with that change.

 

[VBakias]

Thanks, i modified a little:

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

int sig(char [], char []);


void main()
{
char a[30];
char b[30];

scanf("%s", &a);
scanf("%s", &b);


printf("%d\n",sig(a,b));
}

int sig(char a[], char b[])
{

int i;
for (i=0; i<30; i++)
{
if (a != b)
return(0);
}
return(1);
}



I still don't get 2 things
1. with or without the "&" works fine. ?

2. i've declared that the char a[] will be 30 cells.
I can also write: char a[]="hello"; without a number
Is there any way to do something like this: char a[]=read_from_keyboard. Tried this:
char a[];
scanf("%s",&a); // but not working because i've not declared the size of a.

The purpose of this is to sheck first is strlen(a)==strlen(b). If not then definately the strings will not be equal. If yes then i have to check it out.


Tnx

 

[VBakias]

got it