String : Copy and Concatenation: strcpy(), strcat()

Question

 Copy and Concatenation: strcpy(), strcat()

Answer 1

#include <stdio.h> 

#include <string.h>

int main(void) 

{                   /* Always ensure that your string is large enough to contain the characters   * and a terminating NUL character ('\0')!   */  

char mystring[10];

  /* Copy "foo" into `mystring`, until a NUL character is encountered. */  

strcpy(mystring, "foo");  

printf("%s\n", mystring);

  /* At this point, we used 4 chars of `mystring`, the 3 characters of "foo",   * and the NUL terminating byte.   */

  /* Append "bar" to `mystring`. */  

strcat(mystring, "bar");  

printf("%s\n", mystring);

  /* We now use 7 characters of `mystring`: "foo" requires 3, "bar" requires 3   * and there is a terminating NUL character ('\0') at the end.   */

  /* Copy "bar" into `mystring`, overwriting the former contents. */  

strcpy(mystring, "bar");  

printf("%s\n", mystring);

return 0; 

}

Outputs:

foo foobar bar

If you append to or from or copy from an existing string, ensure it is NUL-terminated!

String literals (e.g. "foo") will always be NUL-terminated by the compiler.