//:Vc++6.0 String strncat函数
//功能：按照num数量连接num个字符
//参数：dest 目标字符串 str 连接字符串 num 连接个数
//返回值：目标字符串
#include<stdio.h>
char *strncat(char *dest, const char *str, int num);
int main()
{
char str1[20] = "hello ";
char str2[20] = "world haha";
char str3[20] = "heihei";
strncat(str3, strncat(str1, str2, 6), 5);
printf("str1 = %s\n", str3);
return 0;
}
char *strncat(char *dest, const char *str, int num)
{
if (dest == NULL || str == NULL)
{
perror("dest or str");
return NULL;
}
char *temp = dest;
const char *temp1 = str; //前面必须是const修饰的，否则编译不通过
int len;
while (*(temp1++) != '\0');
len = temp1 - str;
temp1 = str;
while (*(temp++) != '\0');
temp--;
if (num <= 0) //当num值小于0时，不连接
*temp = '\0';
else if (num >= len) //当num值大于字符长度时，全部连接
{
while (*(temp1) != '\0')
{
*(temp++) = *(temp1++);
}
*temp = '\0';
}
else
{
for (int i = 0; i < num; i++)
{
*(temp++) = *(temp1++);
}
*temp = '\0';
}
return dest;
}
//在vc++6.0中的运行结果为：str1 = heiheihello//:~
|
