C Program to Remove all Characters in a String Except Alphabets

In this example, you will learn to remove all the characters from a string entered by the user except the alphabets.

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To understand this example, you should have the knowledge of the following C programming topics:

• C Arrays
• C Programming Strings
• C for Loop
• C while and do…while Loop

Remove Characters in String Except Alphabets

#include 
int main() {
   char line[150];
   
   printf("Enter a string: ");
   fgets(line, sizeof(line), stdin); // take input


   for (int i = 0, j; line[i] != '\0'; ++i) {

      // enter the loop if the character is not an alphabet
      // and not the null character
      while (!(line[i] >= 'a' && line[i] <= 'z') && !(line[i] >= 'A' && line[i] <= 'Z') && !(line[i] == '\0')) {
         for (j = i; line[j] != '\0'; ++j) {

            // if jth element of line is not an alphabet,
            // assign the value of (j+1)th element to the jth element
            line[j] = line[j + 1];
         }
         line[j] = '\0';
      }
   }
   printf("Output String: ");
   puts(line);
   return 0;
}

Output

Enter a string: p2'r-o@gram84iz./
Output String: programiz

This program takes a string input from the user and stores in the line variable. Then, a for loop is used to iterate over characters of the string.

If the character in a string is not an alphabet, it is removed from the string and the position of the remaining characters are shifted to the left by 1 position.