递归可用于一行执行两项任务。下面是stracat()和strcmp()的一行实现。
/* my_strcat(dest, src) copies data of src to dest. To do so, it first reaches end of the string dest using recursive calls my_strcat(++dest, src). Once end of dest is reached, data is copied using
(*dest++ = *src++)? my_strcat(dest, src). */
void my_strcat(char *dest, char *src)
{
(*dest)? my_strcat(++dest, src): (*dest++ = *src++)? my_strcat(dest, src): 0 ;
}
/* driver function to test above function */
int main()
{
char dest[100] = "geeksfor";
char *src = "geeks";
my_strcat(dest, src);
printf(" %s ", dest);
getchar();
}
与my_strcmp()相比，函数my_strcmp()很简单。
/* my_strcmp(a, b) returns 0 if strings a and b are same, otherwise 1. It recursively increases a and b pointers. At any point if *a is not equal to *b then 1 is returned. If we reach end of both strings at the same time then 0 is returned. */
int my_strcmp(char *a, char *b)
{
return (*a == *b && *b == '\0')? 0 : (*a == *b)? my_strcmp(++a, ++b): 1;
}
/* driver function to test above function */
int main()
{
char *a = "geeksforgeeks";
char *b = "geeksforgeeks";
if(my_strcmp(a, b) == 0)
printf(" String are same ");
else
printf(" String are not same ");
getchar();
return 0;
}
上面的函数执行非常基本的字符串连接和字符串比较。这些功能提供的功能与标准库功能不同。
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