C PROGRAMMING PROGRAM • STRINGS

Count the Frequency of a Character in a String

Learn how to count the frequency of a character in a string using a clear C program.

BeginnerStringsLinear scanFrequency

PROBLEM UNDERSTANDING

Input and expected output

Sample input

banana
a

Sample output

'a' occurs 3 time(s)

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    char text[300], target;
    int count = 0;

    fgets(text, sizeof text, stdin);
    printf("Enter character to count: ");
    scanf("%c", &target);
    for (int index = 0; text[index] != '\0'; index++)
        if (text[index] == target) count++;
    printf("'%c' occurs %d time(s)\n", target, count);
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

'a' occurs 3 time(s)

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Compare every string character with the target and increment on equality.
Display the computed result.

Compare every string character with the target and increment on equality.

EFFICIENCY

Time and space complexity

Time complexity

O(n)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.