将两个字符串连起来，不用strcat函数，新手版

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string.h>
int main()
{
int i,m=0,n=0;
char c1, c2;
char str1[80], str2[20];
printf("Input str1:\n");
gets_s(str1);
printf("The str1 is:\n");
for (i = 0; (c1 = str1[i]) != '\0'; i++)
{
m++;
printf("%c", str1[i]);
}
printf("\n");
printf("m=%d\n", m);
printf("Input str2:\n");
gets_s(str2);
printf("The str2 is:\n");
for (i = 0; (c2 = str2[i]) != '\0'; i++)
{
n++;
printf("%c", str2[i]);
}
printf("\n");
printf("n=%d\n",n);
if (n <= 80 - (m + 1))
{
printf("Now we connect str1 and str2:\n");
for (i = 0; i < m + n; i++)
{
c1 = str1[i];
c2 = str2[i];
str1[m + i] = c2;
printf("%c", str1[i]);
}
}
else
printf("There is an error in your input,please try again!");
printf("\n");
return 0;
}