C strcat()

In C programming, the strcat() function contcatenates (joins) two strings.

The function definition of strcat() is:

char *strcat(char *destination, const char *source)

It is defined in the string.h header file.

strcat() arguments

As you can see, the strcat() function takes two arguments:

destination – destination string
source – source string

The strcat() function concatenates the destination string and the source string, and the result is stored in the destination string.

Example: C strcat() function

#include <stdio.h>
#include <string.h>
int main() {
   char str1[100] = "This is ", str2[] = "programiz.com";

   // concatenates str1 and str2
   // the resultant string is stored in str1.
   strcat(str1, str2);

   puts(str1);
   puts(str2);

   return 0;
}

Output

This is programiz.com
programiz.com

Note: When we use strcat(), the size of the destination string should be large enough to store the resultant string. If not, we will get the segmentation fault error.