Yêu cầu:
Viết hàm đếm số phần tử dương trong ma trận số thực

Thuật toán:
1. Viết hàm nhập vào ma trận số thực
2. Viết hàm đếm số phần tử dương trong ma trận số thưc

Code:

```/*********Average of positive elements in matrix*************
*Author: vncoding
*Date : 31/03/2019
************************************************************/

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#define N 100
#define M 100

void ImportData(float[][M], int, int, char*);
void PrintMatrix(float[][M], int, int);
int CntPosInMatrix(float[][M], int, int);
void main()
{
int nRow, nCol;
float average;
float A[N][M];

printf("\nNumber of row: ");
scanf("%d", &nRow);
printf("\nNumber of column: ");
scanf("%d", &nCol);

ImportData(A, nRow, nCol, "A");
PrintMatrix(A, nRow, nCol);

printf("\nCount positive elements in matrix: %d", CntPosInMatrix(A, nRow, nCol));

getch();
}

/*************************************************************
* Function      : CntPosInMatrix()
* Parameter     : A[][M]: input matrix (I)
nRow  : row number   (I)
nCol  : column number(I)
* Return        : int
* Description   : Count positive elements in matrix
*************************************************************/
int CntPosInMatrix(float A[][M], int nRow, int nCol)
{
int iRow, iCol;
int cnt = 0;
for (iRow = 0; iRow < nRow; iRow++)
{
for (iCol = 0; iCol < nCol; iCol++)
{
if (A[iRow][iCol] > 0)
{
cnt++;
}
}
}

return cnt;
}

/*************************************************************
* Function      : ImportData()
* Parameter     : A[][M]: input matrix (I)
nRow  : row number   (I)
nCol  : column number(I)
nameMatrix: matrix name (I)
* Return        : void
* Description   : Import matrix data
*************************************************************/
void ImportData(float Matrix[][M], int nRow, int nCol, char* nameMatrix)
{
int iRow, iCol;
for (iRow = 0; iRow < nRow; iRow++)
for (iCol = 0; iCol < nCol; iCol++)
{
printf("\n%s[%d][%d] = ", nameMatrix, iRow, iCol);
scanf("%f", &Matrix[iRow][iCol]);
}
}

/*************************************************************
* Function      : PrintMatrix()
* Parameter     : Matrix: input matrix (I)
nRow  : row number   (I)
nCol  : column number(I)
* Return        : void
* Description   : Display matrix data
*************************************************************/
void PrintMatrix(float Matrix[][M], int nRow, int nCol)
{
int iRow, iCol;
printf("\nA = ");
for (iRow = 0; iRow < nRow; iRow++)
{
printf("\n");
for (iCol = 0; iCol < nCol; iCol++)
{
printf("\t%.2f\t", Matrix[iRow][iCol]);
}
}
}
```

Kết quả:

```Number of row: 3
Number of column: 4

A[0][0] = 3.4
A[0][1] = -3.4
A[0][2] = 3.6
A[0][3] = 12
A[1][0] = 44
A[1][1] = -3.6
A[1][2] = 0
A[1][3] = -4.7
A[2][0] = 13
A[2][1] = -5.6
A[2][2] = 4.5
A[2][3] = 6.7

A =
3.40            -3.40           3.60            12.00
44.00           -3.60           0.00            -4.70
13.00           -5.60           4.50            6.70
Count positive elements in matrix: 7
```