Lesson 9。

09/Optional03.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+int main() {
+    char idCardNo[18] = {0};
+    int i = 0, sum = 0;
+    int temp = 0;
+    char checkSum = 0;
+    int weigh[17] = {7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2};
+    for (i = 0; i < 18; i++) {
+        idCardNo[i] = getchar();
+    }
+    for (i = 0; i < 17; i++) {
+        temp = ((idCardNo[i] - '0')*weigh[i]) % 11;
+        sum += ((idCardNo[i] - '0')*weigh[i]) % 11;
+    }
+    checkSum = (12 - (sum % 11)) % 11;
+    if (checkSum == 10) {
+        checkSum = 'X';
+    }
+    else {
+        checkSum += '0';
+    }
+    if (checkSum == idCardNo[17]) {
+        printf("合法\n");
+    }
+    else {
+        printf("非法，正确校验位是%c", checkSum);
+    }
+    return 0;
+}