Write a C Program to Replace Last Occurrence of a Character in a String with example.
C Program to Replace Last Occurrence of a Character in a String Example 1
This C program allows the user to enter a string (or character array), and a character value. Next, it will find and replace last occurrence of a character inside a string.
/* C Program to Replace Last Occurrence of a Character in a String */ #include <stdio.h> #include <string.h> int main() { char str[100], ch, Newch; int i, index; index = -1; printf("\n Please Enter any String : "); gets(str); printf("\n Please Enter the Character that you want to Replace : "); scanf("%c", &ch); getchar(); printf("\n Please Enter the New Character : "); scanf("%c", &Newch); for(i = 0; str[i] != '\0'; i++) { if(str[i] == ch) { index = i; } } if(index != -1) { str[index] = Newch; } printf("\n The Final String after Replacing Last occurrence of '%c' with '%c' = %s ", ch, Newch, str); return 0; }

First, we used For Loop to iterate every character in a C Programming String.
for(i = 0; i <= strlen(str); i++) { if(str[i] == ch) { index = i; } }
Next, we used the If Statement to check the index value is not equal to -1. If it is True then execute str[index] = Newch;
str[] = Hello
ch = l
Newch = @
Index = -1
For Loop First Iteration: for(i = 0; i <= strlen(str); i++)
The condition is True because i <= 5.
Within the While Loop, we used If statement to check whether the str[0] is equal to a user-specified character or not
if(str[i] == ch) => if(H == l) – condition is false. So, i value will be incremented, and Index value is still -1.
Second Iteration: for(i = 1; 1 <= 5; 1++)
if(str[i] == ch) => if(e == l) – condition is false. So, i will increment, and Index value is still -1.
Third Iteration: for(i = 2; 2 <= 5; 2++)
if(str[i] == ch) => if(l == l) – condition is True
Index = i
index = 2
Third Iteration: for(i = 3; 3 <= 5; 3++)
if(str[i] == ch) => if(l == l) – condition is True
index = i = 3
Do the same for remaining iterations.
Next, we used the If Statement to check the index value is equal to -1. Here, the condition is True so,
str[index] =Newch
str[3] = @
At last, we used the printf statement to print the final string
printf("\n The Last Occurrence of the Search Element '%c' is at Position %d ", ch, i + 1);
C Program to Replace Last Occurrence of a Character in a String Example 2
This program to replace last character occurrence is the same as above. Here, we just replaced the For Loop with While Loop.
/* C Program to Replace Last Occurrence of a Character in a String */ #include <stdio.h> #include <string.h> int main() { char str[100], ch, Newch; int i, index; index = -1; i = 0; printf("\n Please Enter any String : "); gets(str); printf("\n Please Enter the Character that you want to Replace : "); scanf("%c", &ch); getchar(); printf("\n Please Enter the New Character : "); scanf("%c", &Newch); while(i <= strlen(str)) { if(str[i] == ch) { index = i; } i++; } if(index != -1) { str[index] = Newch; } printf("\n The Final String after Replacing Last occurrence of '%c' with '%c' = %s ", ch, Newch, str); return 0; }
Please Enter any String : tutorial gateway
Please Enter the Character that you want to Replace : t
Please Enter the New Character : #
The Final String after Replacing Last occurrence of 't' with '#' = tutorial ga#eway
C Program to Replace Last Occurrence of a Character in a String Example 3
This program to replace the last character occurrence is the same as the first example. Still, this time, we applied the Functions concept to separate the logic.
/* C Program to Replace Last Occurrence of a Character in a String */ #include <stdio.h> #include <string.h> void Replace_LastOccurrence(char *str, char ch, char Newch); int main() { char str[100], ch, Newch; int i, index; index = -1; printf("\n Please Enter any String : "); gets(str); printf("\n Please Enter the Character that you want to Replace : "); scanf("%c", &ch); getchar(); printf("\n Please Enter the New Character : "); scanf("%c", &Newch); Replace_LastOccurrence(str, ch, Newch); printf("\n The Final String after Replacing Last occurrence of '%c' with '%c' = %s ", ch, Newch, str); return 0; } void Replace_LastOccurrence(char *str, char ch, char Newch) { int i, index; index = -1; for(i = 0; str[i] != '\0'; i++) { if(str[i] == ch) { index = i; } } if(index != -1) { str[index] = Newch; } }
Please Enter any String : c programming
Please Enter the Character that you want to Replace : m
Please Enter the New Character : $
The Final String after Replacing Last occurrence of 'm' with '$' = c program$ing