实现strlen函数

#include <assert.h>
#include <stdio.h>

int mystrlen(const char *str)
{
    assert(str != NULL);
    return ('\0' != *str) ? (mystrlen(str + 1) + 1) : 0;
}

void main()
{
    char *buf = "abcdefghij";
    printf("The length of %s is: %d", buf, mystrlen(buf));
}

 

/*
 * assert prints a diagnostic message when expression evaluates to false (0)
 * and calls abort to terminate program execution.
 * No action is taken if expression is true (nonzero).
 * The diagnostic message includes the failed expression
 * and the name of the source file and line number where the assertion failed.
 */