C program to perform the different operations on strings

In this article we will learn to implement a C program to perform the different operations on strings using functions. A C program is provided below to perform various operations on strings.

/*
 * C program to perform the following operations on strings using functions:
 * i. To insert a sub string in to given main string from a given position.
 * ii. To delete n characters from a given position in a given string.
 * iii. To replace a character from the string either from beginning or ending or at a specified location.
 * Author: P.S.SuryaTeja
*/
#include <stdio.h>
#include <conio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

void insertsubstr(char *str)
{
	char substr[10], newstr[30];
	int pos, strlength;
	int i, j, k;
	strlength = strlen(str);
	printf("\nEnter a substring: ");
	gets(substr);
	printf("\nEnter the index at which the substring should be inserted: ");
	scanf("%d", &pos);
	for(i = 0; i < pos; i++)
	{
		newstr[i] = *str;
		str++;
	}
	for(j = i, k = 0; k < strlen(substr); j++, k++)
		newstr[j] = substr[k];
	for(i = j, k = 0; k < strlength; i++, k++)
	{
		newstr[i] = *str;
		str++;
	}
	newstr[i] = '\0';
	printf("\nNew string after insertion is: ");
	puts(newstr);
}

void deletechars(char *str)
{
	char newstr[20];
	int nchars, pos;
	int i, j, strlength;
	strlength = strlen(str);
	printf("\nEnter no. of characters to be deleted: ");
	scanf("%d", &nchars);
	printf("\nEnter the index from which the characters should be deleted: ");
	scanf("%d", &pos);
	for(i = 0; i < pos; i++)
	{
		newstr[i] = *str;
		str++;
	}
	for(j = 0; j < nchars; j++)
		str++;
	for(j = 0; i < strlength - nchars ; i++, j++)
	{
		newstr[i] = *str;
		str++;
	}
	newstr[i] = '\0';
	printf("\nNew string after deletion is: ");
	puts(newstr);
}

void replacechar(char *str)
{
	int choice, pos, i, strlength;
	char newchar, fake;
	char *tempstr;
	tempstr = str;
	strlength = strlen(str);
	printf("\n1.Replace a character at the beginning.");
	printf("\n2.Replace a character at the end.");
	printf("\n3.Replace a character at any position.");
	printf("\nEnter your choice: ");
	scanf("%d", &choice);
	switch(choice)
	{
		case 1:
			printf("Enter the replacement character: ");
			scanf("%c%c", &fake, &newchar);
			*str = newchar;
			printf("\nNew string after replacement is: ");
			puts(str);
			break;
		case 2:
			printf("Enter the replacement character: ");
			scanf("%c%c", &fake, &newchar);
			for(i = 0; i < strlength - 1; i++)
				str++;
			*str = newchar;
			printf("\nNew string after replacement is: ");
			puts(tempstr);
			break;
		case 3:
			printf("\nEnter the index at which character will be replaced: ");
			scanf("%d", &pos);
			printf("\nEnter the replacement character: ");
			scanf("%c%c", &fake, &newchar);
			for(i = 0; i < pos; i++)
				str++;
			*str = newchar;
			printf("\nNew string after replacement is: ");
			puts(tempstr);
			break;
		default:
			printf("\nInvalid choice");
	}
}

int main(int argc, char **argv)
{
	char str[20];
	printf("Enter a string: ");
	gets(str);
	printf("\n***Inserting substring***");
	printf("\n");
	insertsubstr(str);
	printf("\n***Deleting Characters***");
	printf("\n");
	deletechars(str);
	printf("\n***Replacing a character***");
	printf("\n");
	replacechar(str);
    getch();
    return 0;
}

Input and output for the above program is as follows:

Enter a string: I am a good boy

***Inserting substring***

Enter a substring: bad

Enter the index at which the substring should be inserted: 6

New string after insertion is: I am abad good boy

***Deleting Characters***

Enter no. of characters to be deleted: 3

Enter the index from which the characters should be deleted: 6

New string after deletion is: I am aod boy

***Replacing a character***

1.Replace a character at the beginning.
2.Replace a character at the end.
3.Replace a character at any position.
Enter your choice: 1
Enter the replacement character: U

New string after replacement is: U am a good boy

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.