Basic String Programming Questions

Here are 10 C programming exercises that involve strings:

String Length: Write a program to calculate and print the length of a given string without using the strlen function.
String Reversal: Create a program that reverses a given string. For example, if the input is "hello," the output should be "olleh."
String Concatenation: Implement a function to concatenate two strings without using the standard library function strcat.
String Comparison: Write a program that compares two strings without using the strcmp function and prints whether they are equal or not.
Substring Search: Develop a function to check if a given substring exists in a larger string. Return the position of the first occurrence if found, otherwise return -1.
Palindrome Check: Create a program to determine if a given string is a palindrome (reads the same backward as forward).
Count Vowels and Consonants: Write a function to count the number of vowels and consonants in a given string.
String Tokenization: Implement a program that tokenizes a given sentence into words. Print each word on a new line.
String Compression: Develop a function to compress a string by replacing repeated characters with a single occurrence followed by the count. For example, "aaabbbcc" should become "a3b3c2."
Remove Duplicates: Write a program to remove duplicate characters from a string without using any additional data structures. The resulting string should maintain the order of characters.

These exercises cover a range of string-related concepts and will help you practice and strengthen your skills in C programming. I have solved all of the above with explanatory comments. You should first make a sincere attempt at solving these problems before looking at the solutions.

String Length:

 #include <stdio.h>

 // Function to calculate the length of a string
 int stringLength(const char *str) {
     int length = 0;

     // Iterate through the characters until the null terminator is encountered
     while (str[length] != '\0') {
         length++;
     }

     return length;
 }

 int main() {
     const char *inputString = "Hello, World!";
     int length = stringLength(inputString);

     printf("Length of the string: %d\n", length);

     return 0;
 }

String Reversal:

 #include <stdio.h>

 // Function to reverse a string
 void reverseString(char *str) {
     int length = stringLength(str);
     int i, j;

     // Swap characters from the beginning and end of the string
     for (i = 0, j = length - 1; i < j; i++, j--) {
         char temp = str[i];
         str[i] = str[j];
         str[j] = temp;
     }
 }

 int main() {
     char inputString[] = "Hello";

     // Print the original string
     printf("Original String: %s\n", inputString);

     // Reverse the string and print the result
     reverseString(inputString);
     printf("Reversed String: %s\n", inputString);

     return 0;
 }

String Concatenation:

 #include <stdio.h>

 // Function to concatenate two strings
 void concatenateStrings(char *destination, const char *source) {
     int destLength = stringLength(destination);
     int i, j;

     // Move to the end of the destination string
     for (i = 0; source[i] != '\0'; i++) {
         destination[destLength + i] = source[i];
     }

     // Add null terminator to the end of the concatenated string
     destination[destLength + i] = '\0';
 }

 int main() {
     char str1[50] = "Hello, ";
     const char str2[] = "World!";

     // Concatenate str2 to str1 and print the result
     concatenateStrings(str1, str2);
     printf("Concatenated String: %s\n", str1);

     return 0;
 }

String Comparison:

 #include <stdio.h>

 // Function to compare two strings
 int compareStrings(const char *str1, const char *str2) {
     int i = 0;

     // Compare each character until a mismatch is found or both strings end
     while (str1[i] == str2[i] && str1[i] != '\0') {
         i++;
     }

     // Return the difference between the mismatched characters
     return str1[i] - str2[i];
 }

 int main() {
     const char str1[] = "Hello";
     const char str2[] = "World";

     // Compare str1 and str2 and print the result
     int result = compareStrings(str1, str2);
     printf("Comparison Result: %d\n", result);

     return 0;
 }

Substring Search:

 #include <stdio.h>

 // Function to search for a substring in a string
 int searchSubstring(const char *str, const char *substring) {
     int i, j;

     // Iterate through the string
     for (i = 0; str[i] != '\0'; i++) {
         // Check for substring match starting from the current position
         for (j = 0; substring[j] != '\0' && str[i + j] == substring[j]; j++);

         // If the entire substring is found, return the starting position
         if (substring[j] == '\0') {
             return i;
         }
     }

     // Return -1 if substring is not found
     return -1;
 }

 int main() {
     const char str[] = "Hello, World!";
     const char substring[] = "World";

     // Search for the substring and print the result
     int position = searchSubstring(str, substring);
     if (position != -1) {
         printf("Substring found at position: %d\n", position);
     } else {
         printf("Substring not found.\n");
     }

     return 0;
 }

Palindrome Check:

 #include <stdio.h>
 #include <stdbool.h>

 // Function to check if a string is a palindrome
 bool isPalindrome(const char *str) {
     int length = stringLength(str);
     int i, j;

     // Compare characters from the beginning and end of the string
     for (i = 0, j = length - 1; i < j; i++, j--) {
         if (str[i] != str[j]) {
             return false;
         }
     }

     // If the loop completes without returning, the string is a palindrome
     return true;
 }

 int main() {
     const char str[] = "radar";

     // Check if the string is a palindrome and print the result
     if (isPalindrome(str)) {
         printf("%s is a palindrome.\n", str);
     } else {
         printf("%s is not a palindrome.\n", str);
     }

     return 0;
 }

Count Vowels and Consonants:

 #include <stdio.h>

 // Function to count vowels and consonants in a string
 void countVowelsConsonants(const char *str, int *vowels, int *consonants) {
     *vowels = 0;
     *consonants = 0;

     // Iterate through the string and classify each character
     for (int i = 0; str[i] != '\0'; i++) {
         char ch = str[i];

         // Check if the character is a vowel
         if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' ||
             ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U') {
             (*vowels)++;
         } else if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
             // Check if the character is a consonant
             (*consonants)++;
         }
     }
 }

 int main() {
     const char str[] = "Hello, World!";
     int numVowels, numConsonants;

     // Count vowels and consonants and print the result
     countVowelsConsonants(str, &numVowels, &numConsonants);
     printf("Vowels: %

d\nConsonants: %d\n", numVowels, numConsonants);

return 0; }


8. **String Tokenization:**
```c
#include <stdio.h>
#include <string.h>

// Function to tokenize a string
void tokenizeString(const char *sentence) {
    char copy[100];
    strcpy(copy, sentence);

    // Tokenize the string using strtok
    char *token = strtok(copy, " ");

    // Iterate through tokens and print each one
    while (token != NULL) {
        printf("%s\n", token);
        token = strtok(NULL, " ");
    }
}

int main() {
    const char sentence[] = "This is a sample sentence.";

    // Tokenize the sentence and print each word
    tokenizeString(sentence);

    return 0;
}

String Compression:

 #include <stdio.h>

 // Function to compress a string
 void compressString(char *str) {
     int length = stringLength(str);
     int compressedIndex = 0;

     // Iterate through the string to compress
     for (int i = 0; i < length; i++) {
         char currentChar = str[i];
         int count = 1;

         // Count consecutive occurrences of the current character
         while (i + 1 < length && str[i + 1] == currentChar) {
             i++;
             count++;
         }

         // Append the compressed character and count to the result string
         str[compressedIndex++] = currentChar;
         if (count > 1) {
             // Only append the count if it is greater than 1
             str[compressedIndex++] = count + '0';
         }
     }

     // Add null terminator to the end of the compressed string
     str[compressedIndex] = '\0';
 }

 int main() {
     char str[] = "aaabbbcc";

     // Compress the string and print the result
     compressString(str);
     printf("Compressed String: %s\n", str);

     return 0;
 }

Remove Duplicates:

 #include <stdio.h>

 // Function to remove duplicate characters from a string
 void removeDuplicates(char *str) {
     int hash[256] = {0}; // Assuming ASCII characters

     int i, j = 0;

     // Iterate through the string
     for (i = 0; str[i] != '\0'; i++) {
         // Check if the character has been encountered before
         if (hash[str[i]] == 0) {
             // If not, mark it as encountered and copy it to the result string
             hash[str[i]] = 1;
             str[j++] = str[i];
         }
     }

     // Add null terminator to the end of the modified string
     str[j] = '\0';
 }

 int main() {
     char str[] = "programming";

     // Remove duplicates from the string and print the result
     removeDuplicates(str);
     printf("String after removing duplicates: %s\n", str);

     return 0;
 }

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Basic String Programming Questions