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  1. 123

    To dynamically allocate a 2D array and take user input in C, you can use malloc to allocate memory on the heap. Below is a step-by-step guide with an example.

    Steps to Allocate and Input a 2D Array Dynamically:

    1. Allocate Memory for Rows: Use a pointer-to-pointer (int**) to allocate memory for the rows.

    2. Allocate Memory for Columns: For each row, allocate memory for the columns using malloc.

    3. Take User Input: Use nested loops to input values into the allocated 2D array.

    4. Free Allocated Memory: After usage, free the memory row by row and finally free the pointer-to-pointer.

    Example Code:

    #include <stdio.h>
    #include <stdlib.h>

    int main() {
    int rows, cols;

    // Get dimensions from user
    printf("Enter number of rows: ");
    scanf("%d", &rows);
    printf("Enter number of columns: ");
    scanf("%d", &cols);

    // Allocate memory for rows
    int** array = (int**)malloc(rows * sizeof(int*));
    if (array == NULL) {
    printf("Memory allocation failed!\n");
    return 1;
    }

    // Allocate memory for columns in each row
    for (int i = 0; i < rows; i++) {
    array[i] = (int*)malloc(cols * sizeof(int));
    if (array[i] == NULL) {
    printf("Memory allocation failed!\n");
    return 1;
    }
    }

    // Take input from user
    printf("Enter elements of the 2D array:\n");
    for (int i = 0; i < rows; i++) {
    for (int j = 0; j < cols; j++) {
    printf("Element [%d][%d]: ", i, j);
    scanf("%d", &array[i][j]);
    }
    }

    // Print the array
    printf("\nThe 2D array is:\n");
    for (int i = 0; i < rows; i++) {
    for (int j = 0; j < cols; j++) {
    printf("%d ", array[i][j]);
    }
    printf("\n");
    }

    // Free allocated memory
    for (int i = 0; i < rows; i++) {
    free(array[i]);
    }
    free(array);

    return 0;
    }
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  2. GeeksForGeeks
    https://www.geeksforgeeks.org

    How to dynamically allocate a 2D array in C? - GeeksforGeeks

    Jan 10, 2025 · We can create an array of pointers of size r. Note that from C99, C language allows variable sized arrays. After creating an array of pointers, we can dynamically allocate memory for …

  3. Stack Overflow
    https://stackoverflow.com › questions

    Malloc a 2D array in C - Stack Overflow

    Apr 27, 2016 · It is just that there are too many programmers who think there are no multi-dimensional arrays in C. But just beause "we did it that way all the time" does not mean it is the correct way.

    • Reviews: 3

      Code sample

      array = malloc(sizeof(*array) * ROWS); // COLS is in the `sizeof`
      array = malloc(sizeof(int[ROWS][COLS])); // explicit 2D array notation
      c - How to malloc 2D arrays?Jun 2, 2019
      How do we allocate a 2-D array using One malloc statementJan 4, 2012
      See more results
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      https://learningc.org › chapters

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      https://thelinuxcode.com › two-dimensional-array-malloc-c-programming

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        Aug 10, 2023 · Dynamic array allocation allows creating arrays at runtime with the help of functions like `malloc` or `calloc`, which enable resizing and provide more flexibility in memory usage.

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