C语言 strchr 函数用法

#include <stdio.h>
#include <string.h>

int main ()
{
   const char str[] = "http://www.runoob.com";
   const char ch = &#39;.&#39;;
   char *ret;

   ret = strchr(str, ch);

   printf("|%c| 之后的字符串是 - |%s|\n", ch, ret);
   
   return(0);
}

|.| 之后的字符串是 - |.runoob.com|

//#define  FIRST_DEMO
#define  SECOND_DEMO
#ifdef FIRST_DEMO
#include <stdio.h>
#include <conio.h>
#include <string.h>
#pragma warning (disable:4996)
int main(void)
{
	char string[17];
	char *ptr;
	char c=&#39;T&#39;;
	strcpy(string,"This is a string");
	ptr=strchr(string,c);
	if (ptr)
	{
		printf("The character %c is at position:%d\n",c,ptr-string);
	}
	else
	{
		printf("The character was not found\n");
	}
	getch();
	return 0;
}
#elif defined SECOND_DEMO
#include <stdio.h>
#include <conio.h>
#include <string.h>
#pragma warning (disable:4996)
int main(void)
{
    char answer[100];
	char *p;
	printf("Type something:\n");
	fgets(answer,sizeof answer,stdin);
	if ((p=strchr(answer,&#39;\n&#39;))!=NULL)   /*fgets不会像gets那样自动地去掉结尾的\n，所以程序中手动将\n位置处的值变为\0,代表输入的结束。*/
	{
		*p=&#39;\0&#39;;
	}
	printf("You typed \"%s\"\n",answer);
	getch();
	return 0;
}
#endif