C program to replace all occurrence of a character in a string

Enter a string at run time and read a character to replace at console. Then, finally read a new character that has to be placed in place of an old character where ever it occurs inside the string.

Program1

Following is the C program to replace all occurrence of a character −

 Live Demo

#include <stdio.h> #include <string.h> int main(){    char string[100], ch1, ch2;    int i;    printf("enter a string : ");    gets(string);    printf("enter a character to search : ");    scanf("%c", &ch1);    getchar();    printf("enter a char to replace in place of old : ");    scanf("%c", &ch2);    for(i = 0; i <= strlen(string); i++){       if(string[i] == ch1){          string[i] = ch2;       }    }    printf("
 the string after replace of '%c' with '%c' = %s ", ch1, ch2, string);    return 0; }

Output

When the above program is executed, it produces the following result −

enter a string: Tutorials Point enter a character to search: i enter a char to replace in place of old: % the string after replace of 'i' with '%' = Tutor%als Po%nt enter a string: c programming enter a character to search: m enter a char to replace in place of old: $ the string after replace of 'm' with '$' = c progra$$ing

Program2

Following is the C program to replace at first occurrence −

 Live Demo

#include <stdio.h> #include <string.h> int main(){    char string[100], ch1, ch2;    int i;    printf("enter a string : ");    gets(string);    printf("enter a character to search : ");    scanf("%c", &ch1);    getchar();    printf("enter a char to replace in place of old : ");    scanf("%c", &ch2);    for(i = 0; string[i]!='\0'; i++){       if(string[i] == ch1){          string[i] = ch2;          break;       }    }    printf("
 the string after replace of '%c' with '%c' = %s ", ch1, ch2, string);    return 0; }

Output

When the above program is executed, it produces the following result −

Run 1: enter a string: Tutorial Point enter a character to search: o enter a char to replace in place of old: # the string after replace of 'o' with '#' = Tut#rial Point Run 2: enter a string: c programming enter a character to search: g enter a char to replace in place of old: @ the string after replace of 'g' with '@' = c pro@ramming