{"id":1006,"date":"2024-10-19T13:42:48","date_gmt":"2024-10-19T08:12:48","guid":{"rendered":"https:\/\/codexplained.in\/?p=1006"},"modified":"2025-11-24T15:35:14","modified_gmt":"2025-11-24T10:05:14","slug":"count-frequency-of-elements-in-an-array","status":"publish","type":"post","link":"https:\/\/codexplained.in\/?p=1006","title":{"rendered":"Count Frequency Of Elements In An Array"},"content":{"rendered":"
\n#include <stdio.h>\n\nvoid countFrequency(int arr[], int n) {\n    int freq[n]; \/\/ Array to store frequencies\n    int counted[n]; \/\/ Array to track counted elements\n    int i, j;\n\n    \/\/ Initialize frequency and counted arrays\n    for (i = 0; i < n; i++) {\n        freq[i] = 0;\n        counted[i] = 0;\n    }\n\n    \/\/ Count frequency of each element\n    for (i = 0; i < n; i++) {\n        if (counted[i] == 0) { \/\/ Check if the element is counted\n            freq[i] = 1; \/\/ Start counting this element\n            for (j = i + 1; j < n; j++) {\n                if (arr[i] == arr[j]) {\n                    freq[i]++;\n                    counted[j] = 1; \/\/ Mark as counted\n                }\n            }\n        }\n    }\n\n    \/\/ Print frequencies\n    printf("Element Frequency\\n");\n    for (i = 0; i < n; i++) {\n        if (freq[i] > 0) { \/\/ Print only counted elements\n            printf("%d         %d\\n", arr[i], freq[i]);\n        }\n    }\n}\n\nint main() {\n    int array[] = {10, 20, 10, 30, 20, 10, 40};\n    int n = sizeof(array) \/ sizeof(array[0]);\n    countFrequency(array, n);\n    return 0;\n}\n\n<\/pre><\/div>\n\n\n
Explanation<\/h3>\n\n\n\n
    \n
  1. Include Headers<\/strong>: The program starts by including the standard input-output header (<stdio.h><\/code>).<\/li>\n\n\n\n
  2. Function Definition<\/strong>: The function countFrequency<\/code> takes an array and its size as parameters.<\/li>\n\n\n\n
  3. Initialization<\/strong>:\n
      \n
    • Two arrays, freq<\/code> and counted<\/code>, are declared. freq<\/code> will store the frequency of each element, while counted<\/code> will help track which elements have already been counted.<\/li>\n\n\n\n
    • Both arrays are initialized to zero.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • Count Frequencies<\/strong>:\n
        \n
      • The outer loop iterates through each element of the array.<\/li>\n\n\n\n
      • If an element hasn’t been counted yet (checked via the counted<\/code> array), it initializes its frequency to 1.<\/li>\n\n\n\n
      • The inner loop checks subsequent elements. If a match is found, it increments the frequency for that element and marks the matched element as counted.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
      • Print Results<\/strong>: After counting, the function prints the element and its frequency, ensuring that only counted elements are displayed.<\/li>\n<\/ol>\n\n\n\n
        Output<\/h3>\n\n\n\n
        For the input array {10, 20, 10, 30, 20, 10, 40}<\/code>, the output will be:<\/p>\n\n\n\n
        mathematicaCopy codeElement Frequency\n10         3\n20         2\n30         1\n40         1\n<\/code><\/pre>\n\n\n\n
        This program effectively counts the frequency of each element in the array, achieving O(n\u00b2) time complexity due to the nested loops.<\/p>\n\n\n\n
        <\/p>\n