C语言 strchr()用法及代码示例

本节将讨论 C 编程语言中字符串头的 strchr() 函数。 strchr() 函数用于在原始字符串中查找指定字符的第一次出现。换句话说，strchr() 函数检查原始字符串是否包含定义的字符。如果在字符串中找到该字符，则返回一个指针值；否则，它返回一个空指针。在C语言中使用strchr()函数时，需要在程序中导入<string.h>头文件。

用法

char *strchr (const char *str, int c);

在上面的语法中，一个 strchr() 函数有两个参数：str 和 ch。

str:str 表示要在其中搜索字符的原始字符串。

ch:ch 是字符类型变量，表示在字符串 str 中搜索的字符。

返回值：它返回一个指针值，其中包含给定字符串中第一次出现的字符。

演示 strchr() 函数使用的程序

让我们考虑一个例子来检查给定字符串中字符的出现。

程序1.c

#include <stdio.h>
#include <string.h>
int main ()
{
	const char str[] = "Use strchr() function in C.";
	const char ch = 's'; // it is searched in str[] array
	char *ptr; // declare character pointer ptr
	
	printf (" Original string is:%s \n", str);
	// use strchr() function and pass str in which ch is to be searched
	ptr = strchr( str, ch);
	printf (" The first occurrence of the '%c' in '%s' string  is:'%s' ", ch, str, ptr);
	return 0;
}

输出

Original string is:Use strchr() function in C.
 The first occurrence of the 's' in 'Use strchr() function in C.' string is:'e strchr() function in C.'

在上面的程序中，我们给strchr()函数传递了一个str参数来搜索字符's'，当找到一个字符时，返回一个指针ptr值。 ptr 变量包含来自原始字符串的指定字符的值，直到 ch 变量在字符串中没有获得空字符。

使用 strchr() 函数和 if-else 语句搜索字符的程序

让我们考虑使用 strchr() 函数和 if-else 语句在 C 编程语言的给定字符串中获取第一个字符的出现的示例。

程序1.c

#include <stdio.h>
#include <string.h> // use string.h header file 

int main ()
{
	
	const char *s = "javatpoint"; // initialization of the constant char pointer
	char ch; // declare a ch variable
	
	printf (" Original string:\"%s\" \n ", s); // print the string
	
	// take a character from the user 
	printf ("Please enter a character you want to search in the string:");
	scanf (" %c", &ch;);
	
	// it checks whether the specified character exists in the string
	if ( strchr (s, ch) != NULL )
	{
		printf (" \n '%c' is found in \"%s\" ", ch, s);
		}
	// if the character is not found, the below statement is executed		
	else
		printf (" \n '%c' is not found in \"%s\" ", ch, s);
	
	return 0;	
}

输出

Original string:"javatpoint"
 Please enter a character you want to search in the string:p

 'p' is found in "javatpoint"

2^nd执行：

Original string:"javatpoint"
 Please enter a character you want to search in the string:b

 'b' is not found in "javatpoint"

在上面的程序中，我们传递了一个字符串 "javatpoint" 来搜索指定的字符。这里我们将 'p' 字符作为用户的输入并在字符串中进行搜索。之后，if 语句使用 strchr() 函数检查字符是否出现，如果存在则打印指定的字符。否则，表示在字符串中找不到该字符。

获取给定字符串中每个字符出现的程序

让我们考虑一个示例，使用 strchr() 函数和 C 编程语言的 while 循环打印给定字符串中每个字符的出现次数。

程序3.c

#include <stdio.h>
#include <string.h>
int main ()
{
	// initialize a string
	char str[] = " Welcome to the JavaTpoint site";
	char *ptr; // declare a pointer variable
	int i = 1; // declare and initialize i
	
	// use strchr() function to check the occurrence of the character 
	ptr = strchr (str, 'e' );
	
	// use while loop to checks ptr until it becomes null
	while (ptr != NULL)
	{
		printf (" Given character 'e' found at position %d \n", (ptr - str + 1));
		printf (" Occurrence of the character 'e':%d \n", i);
		printf (" The occurrence of the character 'e' in the string \"%s\" is \"%s\" \n \n", str, ptr);
		
		// use strchr() function to update the position of the string
		ptr = strchr (ptr + 1, 'e');
		i++;
	}
	return 0;
}

输出

Given character 'e' found at position 3
 Occurrence of the character 'e':1
 The occurrence of the character 'e' in the string " Welcome to the JavaTpoint site" is "elcome to the JavaTpoint site"

 Given character 'e' found at position 8	
 Occurrence of the character 'e':2
 The occurrence of the character 'e' in the string " Welcome to the JavaTpoint site" is "e to the JavaTpoint site"

 Given character 'e' found at position 15
 Occurrence of the character 'e':3
 The occurrence of the character 'e' in the string " Welcome to the JavaTpoint site" is "e JavaTpoint site"

 Given character 'e' found at position 31
 Occurrence of the character 'e':4
 The occurrence of the character 'e' in the string " Welcome to the JavaTpoint site" is "e"

相关用法

注：本文由纯净天空筛选整理自 strchr() function in C。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。