11.1

<stdio.h>
#include <string.h>
void change(char *a,char *b,char *c)
{
int i,n,m,k,temp;


n = strlen(b);
k = 0;
m = 0;


//倒序输出字符串
for(i = 0;i < n / 2;i++)
{
temp = b[i];
b[i] = b[n - 1 - i];
b[n - 1 - i] = temp;
}


for(i = 0;a[i] != '\0';i++)
{
c[k++] = a [i];
if(m < n)   //输至数组b的最后字符
c[k++] = b[m++];
}


c[k] = '\0'; //字符串结束标志


}
int main()
{
char s1[10] = "abcdefg";
char s2[10] = "1234";
char t[20];


printf("s1:%s\n",s1);
printf("s2:%s\n",s2);


change(s1,s2,t);


printf("t:%s\n",t);


    return 0;
}