程序代码：

#include <stdio.h>
void strcat(char *string1, char *string2){
    while(*string1 != '\0')
        string1++;
    while(*string2)
    {
        *string1++ = *string2++;

    }
    *string1++ = '\0';
}
int strlen(char *string1){
    int count = 0;
    while(*string1++ != '\0')
        count++;
    return count;
}
int main(void)
{
    char name[100]="wangfeng";
    char *mesg = " is a student!";
    strlen(name);
    puts(name);
    return 0;
}