请教C语言习题-4

main()
{
char s1[80],s2[40];
int i=0,j=0;
printf("\nInput the first string:");
gets(s1);
printf("\nInput the second string:");
gets(s2);
while (s1[i] !='\0')
i++;
while (s2[j] !='\0')
s1[i++]=s2[j++];/* 拼接字符到s1 */
s1[i] ='\0';
printf("\nNew string: %s",s1);
}
程序运行结果：
Input the first string：China
Input the second string:Beijing
New string: ChinaBeijing

void main()
{
char s1[80],s2[40];
int i=0,j=0;
printf("\nInput the first string:");
gets(s1);
printf("\nInput the second string:");
gets(s2);
while (s1[i] !='\0')
i++;

while (s2[j] !='\0')
s1[i++]=s2[j++];

s1[i] ='\0';
printf("\nNew string: %s\n",s1);
}

Input the