Lab: String Manipulation

1. Program to Count Vowels, Consonants, Digits, and Spaces in a Given String (using scanf)

#include <stdio.h>
#include <ctype.h>

int main() {
  char str[100];
  int vowels = 0, consonants = 0, digits = 0, spaces = 0;

  printf("Enter a string: ");
  scanf("%[^\n]s", str); // Using %[^\n] to read the whole line including spaces

  for (int i = 0; str[i] != '\0'; i++) {
    char ch = tolower(str[i]);
    if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
      vowels++;
    } else if (isalpha(ch)) {
      consonants++;
    } else if (isdigit(ch)) {
      digits++;
    } else if (isspace(ch)) {
      spaces++;
    }
  }

  printf("Vowels: %d\n", vowels);
  printf("Consonants: %d\n", consonants);
  printf("Digits: %d\n", digits);
  printf("Spaces: %d\n", spaces);
  
  return 0;
}

2. Program to Remove All Vowels from a Given String (using scanf)

#include <stdio.h>
#include <ctype.h>

int main() {
  char str[100], result[100];
  int j = 0;

  printf("Enter a string: ");
  scanf("%[^\n]s", str); // Using %[^\n] to read the whole line including spaces

  for (int i = 0; str[i] != '\0'; i++) {
    char ch = tolower(str[i]);
    if (!(ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u')) {
      result[j++] = str[i];
    }
  }
  result[j] = '\0'; // Null terminate the result string

  printf("String without vowels: %s\n", result);

  return 0;
}

3. Program to Check Whether a Given String is a Palindrome

#include <stdio.h>
#include <string.h>

int main() {
  char str[100], rev[100];
  int length, flag = 1;

  printf("Enter a string: ");
  scanf("%[^\n]s", str);

  length = strlen(str);
  for (int i = 0; i < length; i++) {
    rev[i] = str[length - i - 1];
  }
  rev[length] = '\0'; // Null terminate the reversed string

  for (int i = 0; i < length; i++) {
    if (tolower(str[i]) != tolower(rev[i])) {
      flag = 0;
      break;
    }
  }

  if (flag)
    printf("The string is a palindrome.\n");
  else
    printf("The string is not a palindrome.\n");

  return 0;
}

4. Program to Convert a Given String to Uppercase Without Using strupr()

#include <stdio.h>
#include <ctype.h>

int main() {
  char str[100];

  printf("Enter a string: ");
  scanf("%[^\n]s", str);

  for (int i = 0; str[i] != '\0'; i++) {
    str[i] = toupper(str[i]);
  }

  printf("Uppercase string: %s\n", str);

  return 0;
}

5. Program to Find the Frequency of Each Character in a String

#include <stdio.h>
#include <string.h>

int main() {
  char str[100];
  int freq[256] = {0}; 

  printf("Enter a string: ");
  scanf("%[^\n]s", str);

  for (int i = 0; str[i] != '\0'; i++) {
    freq[(unsigned char)str[i]]++;
  }

  printf("Character frequencies:\n");
  for (int i = 0; i < 256; i++) {
    if (freq[i] != 0) {
      printf("%c: %d\n", i, freq[i]);
    }
  }

  return 0;
}