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C program to find the highest frequency of a character in the given string

Here, we are going to learn how to find the highest frequency of a character in the given string in C programming language?
Submitted by Nidhi, on July 20, 2021

Problem statement

Read a string from the user and find the highest frequency of a character in the given string using C program.

C program to find the highest frequency of a character in the given string

The source code to find the highest frequency of a character in the given string is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.

// C program to find the highest frequency of a character
// in the given string

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

void printHighestFrequency(char* str)
{
    int i = 0;
    int j = 0;
    int k = 0;

    int len = 0;
    int high = 0;
    int index = 0;
    int flag = 0;

    char str1[64];
    int cnt[64] = { 0 };

    len = strlen(str);

    while (i < len) {
        if (i == 0) {
            str1[j++] = str[i];
            cnt[j - 1]++; // = cnt[j - 1] + 1;
        }
        else {
            for (k = 0; k < j; k++) {
                if (str[i] == str1[k]) {
                    cnt[k]++;
                    flag = 1;
                }
            }

            if (flag == 0) {
                str1[j++] = str[i];
                cnt[j - 1]++;
            }
            flag = 0;
        }
        i++;
    }

    for (i = 0; i < j; i++) {
        if ((i == 0) && (str1[i] != ' ')) {
            high = cnt[i];
            continue;
        }

        if ((high < cnt[i]) && (str1[i] != ' ')) {
            high = cnt[i];
            index = i;
        }
    }
    printf("Character '%c' is repeted %d time\n", str1[index], cnt[index]);
}

int main()
{
    char str[64];
    printf("Enter the string: ");
    scanf(" %[^\n]s", str);

    printHighestFrequency(str);

    return 0;
}

Output

RUN 1:
Enter the string: this is india.
Character 'i' is repeted 4 time

RUN 2:
Enter the string: is are am
Character 'a' is repeted 2 time

RUN 3:
Enter the string: Hello world, how are you?
Character 'o' is repeted 4 time

Explanation

In the above program, we created two functions printHighestFrequency() and main(). The printHighestFrequency() function is used to find the highest frequency character in string.

In the main() function, we read a string from the user and called the printHighestFrequency() function and printed the highest frequency character in the string on the console screen.

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