#include <stdio.h>

#define MAX_LEN 1000

void mystrncpy(char *s, char *t, int n) {

char *pt = t;

while (*pt != '\0' && pt < t + n) {

*s = *pt;

pt++;

s++;

}

}

void mystrncat(char *s, char *t, int n) {

while (*s != '\0') {

s++;

}

char *pt = t;

while (pt < t + n && *pt != '\0') {

*s = *pt;

pt++;

s++;

}

*s = '\0';

}

int mystrncmp(char *s, char *t, int n) {

char *pt = t;

while (pt < t + n && *pt != '\0' && *s != '\0' && *pt == *s) {

pt++;

s++;

}

if (pt == t + n) {

return 0;

}

return *s - *pt;

}

int main() {

char s1[MAX_LEN] = "abcdefg";

char *t1 = "xxx";

mystrncpy(s1, t1, 2);

printf("%s\n", s1);

printf("----\n");

char s3[MAX_LEN] = "abcd";

char *t3 = "efg";

mystrncat(s3, t3, 3);

printf("%s\n", s3);

char s4[MAX_LEN] = "abcd";

char *t4 = "efg";

mystrncat(s4, t4, 1);

printf("%s\n", s4);

printf("----\n");

char s5[MAX_LEN] = "abcdef";

char *t5 = "abca";

printf("%d\n", mystrncmp(s5, t5, 4));

}