I tried to read and print a matrix using an external function (from another c file), the thing is that I want to read the matrix dimensions in the function and store them in the main function, how can I do this?
Do I need to return an array with the m and n dimensions of the matrix or can I access the variables that I created in main and change their value within the external function? (I prefer if someone would explain the second) I don't actually know how to use pointers and stuff. Sorry for my English, I'm not a native speaker, also thanks for your response
The second and the third functions are in an external function.c file
int main(){
int num_of_rows, num_of_columns;
int matrix[10][10];
read_matrix(num_of_rows, num_of_columns, matrix);
print_matrix(num_of_rows, num_of_columns, matrix);
printf("\n Press any key to exit the program: ");
_getch();
return 0;
}
void read_matrix(int num_of_rows, int num_of_columns, int matrix[10][10]){
int i,j;
printf("\nPlease specify the number of rows:");
scanf("%d", &num_of_rows);
printf("\nPlease specify the number of columns: ");
scanf("%d", &num_of_columns);
printf("\nPlease introduce the matrix elements below:\n");
for(i=0; i<num_of_rows; i++){
for(j=0; j<num_of_columns; j++){
printf("matrix[%d][%d]= ", i, j);
scanf("%d", &matrix[i][j]);
}
}
}
void print_matrix(int num_of_rows, int num_of_columns, int matrix[10][10]){
int i,j;
for(i=0; i<num_of_rows; i++){
for(j=0; j<num_of_columns; j++){
printf("matrix[%d][%d]= %d", i, j, matrix[i][j]);
}
}
}
Parameters are passed by value in C.
In read_matrix, the num_of_rows parameter is a local variable. Even if you modify it, the caller won't see anything change. Same for num_of_columns.
You want this:
void read_matrix(int *num_of_rows, int *num_of_columns, int matrix[10][10]) {
// ^ add * ^ add *
...
scanf("%d", num_of_rows); // << remove the &
printf("\nPlease specify the number of columns: ");
scanf("%d", num_of_columns); // << remove the &
...
for (i = 0; i < *num_of_rows; i++) {
// ^add *
for (j = 0; j < *num_of_columns; j++) {
// ^add *
and in main:
read_matrix(&num_of_rows, &num_of_columns, matrix);
// ^ ^ add the &s
This is basic knowledge that is covered in your C learning material. Most likely in the chapter dealing with pointers and the one dealing with function calls.
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