Reference: C array to a transfer function
Reference: C language dimensional array as a function of transmission parameters
to sum up:
One-dimensional array parameters, may be an address, arr [], [n] arr
Two-dimensional array is more complex, the need to provide value for the column, otherwise it will error, refer to the above URL
#include <stdio.h>
#include <stdlib.h>
void myFunc1(int length, int *arr) {
for (int i = 0; i < length; i++) {
printf("%d ", arr[i]);
}
printf("\n");
return;
}
void myFunc2(int length, int arr[]) {
for (int i = 0; i < length; i++) {
printf("%d ", arr[i]);
}
printf("\n");
return;
}
void myFunc3(int length, int arr[length]) {
for (int i = 0; i < length; i++) {
printf("%d ", arr[i]);
}
printf("\n");
return;
}
void myFunc4(int row, int column, int *arr2) {
for (int i = 0; i < row; i++) {
for (int j = 0; j < column; j++) {
printf("arr2[%d][%d] = %d ", i, j, *(arr2 + i*column + j));
}
printf("\n");
}
return;
}
void myFunc5(int row, int column, int arr2[][column]) {
for (int i = 0; i < row; i++) {
for (int j = 0; j < column; j++) {
printf("arr2[%d][%d] = %d ", i, j, arr2[i][j]);
}
printf("\n");
}
return;
}
int main() {
int arr[5] = {1, 2, 3, 4, 5};
printf("Parameter is pointer:\n");
myFunc1(5, &arr[0]); // ok with arr
printf("Parameter is array[]:\n");
myFunc2(5, &arr[0]); // ok with arr
printf("Parameter is array[length]:\n");
myFunc3(5, &arr[0]); // ok with arr
int arr2[2][3] = {{1, 2, 3}, {4, 5, 6}};
printf("Parameter is pointer:\n");
myFunc4(2, 3, arr2[0]); // &arr2[0][0] is ok, but arr2 is not ok
// *arr2 is ok.
// but actually they have the same address
printf("Parameter is pointer:\n");
myFunc5(2, 3, arr2); // not ok with arr2[0]
// not ok with &arr2[0][0]
printf("\narr2 = %p\n", arr2);
printf("arr2[0] = %p\n", arr2[0]);
printf("*arr2 = arr2[0] = %p\n", *arr2);
printf("arr2[0][0] = %p\n", &arr2[0][0]);
printf("**arr2 = *arr2[0] = arr2[0][0] = %p\n\n", &arr2[0][0]);
printf("address of this two-dimentional array:\n");
printf("arr2 = %p\n", arr2);
for (int i = 0; i < 2; i++) {
printf(" arr2[%d] = %p\n", i, arr2[0]);
for (int j = 0; j < 3; j++) {
printf(" arr2[%d][%d] = %p ", i, j, &arr2[i][j]);
}
printf("\n");
}
printf("we can use the unexisted element, interesting!\n");
printf("*arr2 means arr2[0], the first row.\n");
printf("**arr2 means *arr2[0] means arr2[0][0], the first element of the first row.\n");
printf("arr2[1][0] = %d\n", arr2[1][0]);
printf("arr2[0][3] = %d\n", arr2[0][3]);
printf("*(*(arr2 + 1) + 0) = %d\n", *(*(arr2 + 1) + 0));
printf("*(*(arr2 + 0) + 3) = %d\n", *(*(arr2 + 0) + 3));
printf("*(arr2[0] + 1*3 + 0) = %d\n", *(arr2[0] + 1*3 + 0));
printf("*(*arr2 + 1*3 + 0) = %d\n", *(*arr2 + 1*3 + 0));
printf("*(&arr2[0][0] + 1*3 + 0) = %d\n", *(&arr2[0][0] + 1*3 + 0));
printf("*(&arr2[0][0] + 3) = %d\n", *(&arr2[0][0] + 3));
return 0;
}
output：
Parameter is pointer:
1 2 3 4 5
Parameter is array[]:
1 2 3 4 5
Parameter is array[length]:
1 2 3 4 5
Parameter is pointer:
arr2[0][0] = 1 arr2[0][1] = 2 arr2[0][2] = 3
arr2[1][0] = 4 arr2[1][1] = 5 arr2[1][2] = 6
Parameter is pointer:
arr2[0][0] = 1 arr2[0][1] = 2 arr2[0][2] = 3
arr2[1][0] = 4 arr2[1][1] = 5 arr2[1][2] = 6
arr2 = 0x7ffc6bdc38a0
arr2[0] = 0x7ffc6bdc38a0
*arr2 = arr2[0] = 0x7ffc6bdc38a0
arr2[0][0] = 0x7ffc6bdc38a0
**arr2 = *arr2[0] = arr2[0][0] = 0x7ffc6bdc38a0
address of this two-dimentional array:
arr2 = 0x7ffc6bdc38a0
arr2[0] = 0x7ffc6bdc38a0
arr2[0][0] = 0x7ffc6bdc38a0 arr2[0][1] = 0x7ffc6bdc38a4 arr2[0][2] = 0x7ffc6bdc38a8
arr2[1] = 0x7ffc6bdc38a0
arr2[1][0] = 0x7ffc6bdc38ac arr2[1][1] = 0x7ffc6bdc38b0 arr2[1][2] = 0x7ffc6bdc38b4
we can use the unexisted element, interesting!
*arr2 means arr2[0], the first row.
**arr2 means *arr2[0] means arr2[0][0], the first element of the first row.
arr2[1][0] = 4
arr2[0][3] = 4
*(*(arr2 + 1) + 0) = 4
*(*(arr2 + 0) + 3) = 4
*(arr2[0] + 1*3 + 0) = 4
*(*arr2 + 1*3 + 0) = 4
*(&arr2[0][0] + 1*3 + 0) = 4
*(&arr2[0][0] + 3) = 4