How to make the actress transposed in C language

Question

Write a program that reads all the elements of an N × N matrix and shows the matrix and its transposition on the screen. Note: The size (N) of the matrix must be read from the keyboard and its allocation must be dynamic through the malloc function.

#include <stdio.h>

#include <stdlib.h>

#define T_BUFFER 512

int main(void)

{

    int *numeros, q_linhas = 0, q_colunas = 0, linhas, colunas;

    char buffer[T_BUFFER];

    /* Pega a quantidade de linhas da matriz */

    do {

        printf("Digite a quantidade de linhas da matriz\n");

        if (fgets(buffer, T_BUFFER, stdin) != NULL) {

            if (buffer[0] != '\n') {

                if (sscanf(buffer, "%i", &q_linhas) != 1) {

                    printf("Digite um numero\n");

                }

            } else {

                printf("Digite uma entrada valida!\n");

            }

        }

    } while (q_linhas <= 0);

    /* Pega a quantidade de colunas da matriz */

    do {

        printf("Digite a quantidade de colunas da matriz\n");

        if (fgets(buffer, T_BUFFER, stdin) != NULL) {

            if (buffer[0] != '\n') {

                if (sscanf(buffer, "%i", &q_colunas) != 1) {

                    printf("Digite um numero\n");

                }

            } else {

                printf("Digite uma entrada valida!\n");

            }

        }

    } while (q_colunas <= 0);

    /* Reserva memoria para a matriz */

    numeros = malloc(sizeof(*numeros)*q_linhas*q_colunas);

    if (numeros == NULL) {

        perror("Erro ao reservar memoria!");

        exit(EXIT_FAILURE);

    }

    /* Lê a matriz do úsuario */

    for (linhas = 0; linhas < q_linhas; linhas++) {

        for (colunas = 0; colunas < q_colunas; colunas++) {

            int pega_novamente = 1;

            /* Pega um numero */

            do {

                printf("[%i][%i]\n", linhas, colunas);

                if (fgets(buffer, T_BUFFER, stdin) != NULL) {

                    if (buffer[0] != '\n') {

                        if (sscanf(buffer, "%i", &numeros[(linhas*q_colunas)+colunas]) == 1) {

                            pega_novamente = 0;     /* Sai do "do {} while()" */

                        }

                    } else {

                        printf("Digite uma entrada valida!\n");

                    }

                }

            } while (pega_novamente);

        }

    }

    /* Mostra a matriz */

    printf("Matriz digitada\n");

    for (linhas = 0; linhas < q_linhas; linhas++) {

        for (colunas = 0; colunas < q_colunas; colunas++) {

            printf("%i,", numeros[(linhas*q_colunas)+colunas]);

        }

        putchar('\n');

    }

    getchar();      /* Espera o enter */

  /* Libera a memoria */

    free(numeros);

    return(0);

}

Answer 1

There are multiple problems here.

• Apparently you do not understand the concept of a matrix. (You read one line and one column in your code, not line * column numbers.)
• You don't seem to understand what the transpose of a matrix is. (You're trying to print the same matrix that you store, not the transpose of it.)
• When you allocate memory, you (wrongly) allocate lines * columns integer pointers, while you should have allocated lines * columns integers (not pointers). For your luck, they have the same size (4-8 bytes depending on 32/64 bit architecture). Nevertheless, the logic is wrong.
  Furthermore, malloc returns a void*, you need to cast it to int pointer.

A simple solution (no user input check) would be something like this:

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

int main()
{
    int rows;
    printf("Please enter N (the number of columns and rows) for a square matrix: ");
    scanf("%d", &rows);
    const int columns = rows;
    
    int **matrix = (int**)malloc(sizeof(int*) * rows);  // Row-major matrix
    for (int rowIndex = 0; rowIndex < rows; rowIndex++)
    {
        matrix[rowIndex] = (int*)malloc(sizeof(int) * columns);
        for (int columnIndex = 0; columnIndex < columns; columnIndex++)
        {
            printf("[%d][%d] = ", rowIndex + 1, columnIndex + 1);
            scanf("%d", &matrix[rowIndex][columnIndex]);
        }
    }

    for (int rowIndex = 0; rowIndex < rows; rowIndex++)
    {
        for (int columnIndex = 0; columnIndex < columns; columnIndex++)
            printf("%d\t", matrix[columnIndex][rowIndex]); // The transpose of a matrix is where the rows are turned into columns and vice versa

        printf("\n");
    }

    for (int rowIndex = 0; rowIndex < rows; rowIndex++)
        free(matrix[rowIndex]);
    free(matrix);
    
    return 0;
}

Answer 2

#include<stdio.h>

int main()

{

int a[20][20], i, j, m, n;

printf("enter size of row and column : ");

scanf("%d%d",&m,&n);

printf("enter array elements : ");

for(i=0;i<m;i++)

{

for(j=0;j<n;j++)

{

scanf("%d",&a[i][j];

}

}

printf("array elements are : );

for(i=0;i<m;i++)

{

for(j=0;j<n;j++)

{

printf("%3d",a[i][j]);

}

}

printf("transpose matrix is : );

for(i=0;i<m;i++)

{

for(j=0;j<n;j++)

{

printf("%d",a[j][i]);

}

}

}