strchr() function in C

This section will discuss the strchr() function of string headers in the C programming language. An strchr() function is used to find the first occurrence of a specified character within the original string. In other words, an strchr() function checks whether the original string contains defined characters. If the character is found inside the string, it returns a pointer value; otherwise, it returns a null pointer. While using the strchr() function in the C programming language, we need to import the <string.h> header file in the program.

Syntax

In the above syntax, an strchr() function has two parameters: str and ch.

str: A str represents the original string in which the character is to be searched.

ch: A ch is a character type variable representing a character searched in the string str.

Return value: It returns a pointer value containing the first occurrence of the character in the given string.

Program to demonstrate the use of a strchr() function

Let's consider an example to check the occurrence of a character in the given string.

Program1.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;
}

Output

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.'

In the above program, we pass an str parameter to the strchr() function to search for character 's', and when a character is found, it returns a pointer ptr value. A ptr variable contains a value from the specified character of the original string until the ch variable does not get a null character in the string.

Program to search a character using the strchr() function and if-else statement

Let's consider an example to get the occurrence of the first character using the strchr() function and if-else statement in a given string of the C programming language.

Program1.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;	
}

Output

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

 'p' is found in "javatpoint"

2^nd execution:

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

 'b' is not found in "javatpoint"

In the above program, we pass a string "javatpoint" to search for a specified character. Here we take the 'p' character as input from the user and search in the string. After that, the if statement checks for the occurrence of the character using the strchr() function and prints the specified character if it exists. Otherwise, it indicates that the character is not found in the string.

Program to get the occurrence of each character in a given string

Let's consider an example to print the occurrence of each character in a given string with strchr() function and while loop of C programming language.

Program3.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;
}

Output

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"

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