Top 10 String programs in C

KT Sessions September 29, 2023

Let's dive into the fascinating world of C programming with strings. Below are 15 important programs that deal with strings.

1. Length of a String 📏

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

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

    return 0;
}

2. Concatenate Two Strings 🧲

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

int main() {
    char str1[50], str2[50];

    printf("Enter the first string: ");
    gets(str1);

    printf("Enter the second string: ");
    gets(str2);

    strcat(str1, str2);

    printf("Concatenated string: %s\n", str1);

    return 0;
}

3. Compare Two Strings 🤔

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

int main() {
    char str1[50], str2[50];

    printf("Enter the first string: ");
    gets(str1);

    printf("Enter the second string: ");
    gets(str2);

    int result = strcmp(str1, str2);

    if (result == 0) {
        printf("Strings are equal.\n");
    } else {
        printf("Strings are not equal.\n");
    }

    return 0;
}

4. Copy One String to Another 📝

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

int main() {
    char source[50], destination[50];

    printf("Enter a string: ");
    gets(source);

    strcpy(destination, source);

    printf("Copied string: %s\n", destination);
 
    return 0;
}

5. Reverse a String ↩️

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    strrev(str);

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

    return 0;
}

6. Convert String to Uppercase 🔠

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    strupr(str);

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

    return 0;
}

7. Convert String to Lowercase 🔡

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    strlwr(str);

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

    return 0;
}

8. Check for Palindrome 🔄

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    int len = strlen(str);
    int isPalindrome = 1;

    for (int i = 0; i < len / 2; i++) {
        if (str[i] != str[len - i - 1]) {
            isPalindrome = 0;
            break;
        }
    }

    if (isPalindrome) {
        printf("Palindrome!\n");
    } else {
        printf("Not a palindrome.\n");
    }

    return 0;
}

9. Count Vowels and Consonants 🗣️

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    int vowels = 0, consonants = 0;
    int len = strlen(str);

    for (int i = 0; i < len; i++) {
        char ch = str[i];
        if (ch >= 'a' && ch <= 'z') {
            if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
                vowels++;
            } else {
                consonants++;
            }
        } else if (ch >= 'A' && ch <= 'Z') {
            if (ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U') {
                vowels++;
            } else {
                consonants++;
            }
        }
    }

    printf("Vowels: %d, Consonants: %d\n", vowels, consonants);

    return 0;
}

10. Count Words in a String 📊

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    int words = 1;
    int len = strlen(str);

    for (int i = 0; i < len; i++) {
        if (str[i] == ' ') {
            words++;
        }
    }

    printf("Number of words: %d\n", words);

    return 0;
}

11. Replace Substring 🔄

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

int main() {
    char str[100], old[50], new[50];

    printf("Enter a string: ");
    gets(str);

    printf("Enter the substring to replace: ");
    gets(old);

    printf("Enter the new substring: ");
    gets(new);

    char *pos = strstr(str, old);

    if (pos != NULL) {
        int index = pos - str;
        memmove(pos + strlen(new), pos + strlen(old), strlen(pos + strlen(old)) + 1);
        strncpy(pos, new, strlen(new));
    }

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

    return 0;
}

12. Remove Spaces from a String 

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    int len = strlen(str);

    for (int i = 0; i < len; i++) {
        if (str[i] == ' ') {
            memmove(&str[i], &str[i + 1], len - i);
            len--;
            i--;
        }
    }

    printf("String without spaces: %s\n", str);

    return 0;
}

13. Extract Substring 📤

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

int main() {
    char str[100];
    int start, length;

    printf("Enter a string: ");
    gets(str);

    printf("Enter the starting position: ");
    scanf("%d", &start);

    printf("Enter the length of the substring: ");
    scanf("%d", &length);

    char substr[length + 1];

    strncpy(substr, str + start, length);
    substr[length] = '\0';

    printf("Extracted substring: %s\n", substr);

    return 0;
}

14. Frequency of Each Character 📊

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

int main() {
    char str[100];

    printf("Enter a string: ");
    gets(str);

    int frequency[128] = {0};
    int len = strlen(str);

    for (int i = 0; i < len; i++) {
        frequency[str[i]]++;
    }

    printf("Character frequencies:\n");

    for (int i = 0; i < 128; i++) {
        if (frequency[i] > 0) {
            printf("%c: %d\n", i, frequency[i]);
        }
    }

    return 0;
}

15. Check Anagram ✨

Determines if two entered strings are anagrams (contain the same characters with the same frequency).

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

int main() {
    char str1[50], str2[50];

    printf("Enter the first string: ");
    gets(str1);

    printf("Enter the second string: ");
    gets(str2);

    int len1 = strlen(str1);
    int len2 = strlen(str2);

    if (len1 != len2) {
        printf("Not anagrams.\n");
        return 0;
    }

    int frequency[128] = {0};

    for (int i = 0; i < len1; i++) {
        frequency[str1[i]]++;
        frequency[str2[i]]--;
    }

    for (int i = 0; i < 128; i++) {
        if (frequency[i] != 0) {
            printf("Not anagrams.\n");
            return 0;
        }
    }

    printf("Anagrams!\n");

    return 0;
}

Feel free to explore and modify these programs to deepen your understanding of C string manipulation! Happy coding! 🚀💻 #CStringManipulation #CProgramming #LearnToCod

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