diff --git a/check.c b/check.c
new file mode 100644
index 0000000..38b86a4
--- /dev/null
+++ b/check.c
@@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <time.h>
+
+void output(int board[9][9]){
+    int i;
+    for(i = 0;i < 9 ;i++){
+        if(i %3 == 0){
+            printf("|-----------------------|\n");
+        }
+        printf("| %d %d %d | %d %d %d | %d %d %d |\n",
+        board[i][0],board[i][1],board[i][2],board[i][3],board[i][4],board[i][5],board[i][6],board[i][7],board[i][8]);
+    }
+    printf("|-----------------------|\n");
+}
+
+
+
+void shuffleArray(int array[], int size) {
+    for (int i = size - 1; i > 0; i--) {
+        int j = rand() % (i + 1);
+        int temp = array[i];
+        array[i] = array[j];
+        array[j] = temp;
+    }
+}
+
+
+void create(int board[9][9]){
+    srand(time(NULL)); 
+    int index = 0;
+    for (int r = 0; r < 9; r+=3){
+        int nums[9] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
+        shuffleArray(nums, 9);
+        for (int i = r; i < r+3; i++) {
+            for (int j = 0; j < 9; j += 3) {
+                board[i][j] = nums[index++];
+                if (index >= 9) {
+                    index = 0;
+            }
+        }
+    }
+    }
+    for(int j = 0;j < 9;j++){
+       shuffleArray(board[j], 9);
+    }
+}
+
+
+void check(int matrix[9][9]) {
+
+    for (int i = 0; i < 9; i++) {
+        int count[10] = {0}; 
+        for (int j = 0; j < 9; j++) {
+            int num = matrix[i][j];
+            if (num != 0) {
+                count[num]++;
+                if (count[num] > 1) {
+                    printf("False: The number %d in the row %d has been used!\n", num, i + 1);
+                    return;
+                }
+            }
+        }
+    }
+
+
+    for (int j = 0; j < 9; j++) {
+        int count[10] = {0};
+        for (int i = 0; i < 9; i++) {
+            int num = matrix[i][j];
+            if (num != 0) {
+                count[num]++;
+                if (count[num] > 1) {
+                    printf("False: The number %d in the col %d has been used!\n", num, j + 1);
+                    return;
+                }
+            }
+        }
+    }
+
+    for (int block = 0; block < 9; block++) {
+        int count[10] = {0};
+        int startRow = (block / 3) * 3;
+        int startCol = (block % 3) * 3;
+        for (int i = startRow; i < startRow + 3; i++) {
+            for (int j = startCol; j < startCol + 3; j++) {
+                int num = matrix[i][j];
+                if (num != 0) {
+                    count[num]++;
+                    if (count[num] > 1) {
+                        printf("False: The number %d in the block %d has been used!\n", num, block + 1);
+                        return;
+                    }
+                }
+            }
+        }
+    }
+
+    printf("True: Valid initial Sudoku matrix!\n");
+}
+
+int main() {
+
+    int matrix[9][9] = {0};
+    create(matrix);
+    printf("The original Sudoku matrix: \n");
+    output(matrix);
+    check(matrix);
+
+    return 0;
+}
\ No newline at end of file