cs24-20fa strlen

Introduction to Computing Systems (Fall 2020)


strlen - calculate the length of a string


#include <string.h>

size_t strlen(const char *s);


The strlen() function calculates the length of the string pointed to by s, excluding the terminating null byte (‘\0’). Note that strlen() stops counting characters as soon as it encounters a null byte.


#include <assert.h>
#include <string.h>

int main() {
    char s[7] = "hello!";
    assert(strlen(s) == 6);

Return Value

Upon completion, the strlen() function returns the number of characters in the string pointed to by s.

See Also

strcpy(), strncpy(), strcmp()