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Terminate any string from given index in C language

By: IncludeHelp, on 03 MAR 2017

Learn: How to terminate any string from a given index using NULL character.

This is a simple C language trick, by using this you can terminate any string from given index by assigning NULL.

We are aware that string is terminated with NULL, if we are reading a string from the keyboard, the associated function like (scanf, fgets, gets...) inserts a NULL character at the end of the string, like these functions we can also insert NULL at any index to terminate the string.

Let suppose there is a string "Hello world" and you want to keep only "Hello" in the original string (character array) variable. You can assign NULL at the index 5 (counting from 0) and string will be terminated.

Consider this example

#include <stdio.h>
int main()
{
	char str[]="Hello world";
	
	printf("str before terminating: %s\n",str);
	//assign NULL at index 5
	str[5]='\0';
	printf("str after terminating: %s\n",str);
	
	return 0;	
}

Output

str before terminating: Hello world 
str after terminating: Hello

Using user define function

#include <stdio.h>

//declaration
void terminate(char *str,int index);

int main()
{
	char str[]="Hello world";
	
	printf("str before terminating: %s\n",str);
	//function calling
	terminate(str,5);
	printf("str after terminating: %s\n",str);
	
	return 0;	
}

//definition
void terminate(char *str,int index){
	str[index]='\0';
}