需要反馈：信用 (Pset1- CS50x)
Need Feedback : Credit (Pset1- CS50x)
#include <stdio.h>
#include <cs50.h>
#include <math.h>
int main(void) {
long int number;
int count = 0; // starting the count counter
do {
number = get_long("Please enter your 13-16 digit credit card number: \n"); //getting input from the user
} while (number <= 0);
int d1 = number % 10; //separating digit number 1
int d2 = ((number % 100) / 10); //separating digit number 2
int d3 = ((number % 1000) / 100); //separating digit number 3
int d4 = ((number % 10000) / 1000); //separating digit number 4
int d5 = ((number % 100000) / 10000); //separating digit number 5
int d6 = ((number % 1000000) / 100000); //separating digit number 6
int d7 = ((number % 10000000) / 1000000); //separating digit number 7
int d8 = ((number % 100000000) / 10000000); //separating digit number 8
int d9 = ((number % 1000000000) / 100000000); //separating digit number 9
int d10 = ((number % 10000000000) / 1000000000); //separating digit number 10
int d11 = ((number % 100000000000) / 10000000000); //separating digit number 11
int d12 = ((number % 1000000000000) / 100000000000); //separating digit number 12
int d13 = ((number % 10000000000000) / 1000000000000); //separating digit number 13
int d14 = ((number % 100000000000000) / 10000000000000); //separating digit number 14
int d15 = ((number % 1000000000000000) / 100000000000000); //separating digit number 15
int d16 = ((number % 10000000000000000) / 1000000000000000); //separating digit number 16
int last13 = number / 1000000000000; //finding the last one digit of 13 digit VISA
int last15 = number / 10000000000000; //finding the last two digit of 15 digit AMEX
int last16v = number / 1000000000000000; //finding the last one digit of 16 digit VISA
int last16m = number / 100000000000000; //finding the last two digit of 16 digit MASTERCARD
int a2 = (d2 * 2);
int a4 = (d4 * 2);
int a6 = (d6 * 2);
int a8 = (d8 * 2);
int a10 = (d10 * 2);
int a12 = (d12 * 2);
int a14 = (d14 * 2);
int a16 = (d16 * 2);
if (a2 >= 10) { // separating the digits of the multiple
int a11a = (a2 % 100) / 10;
int a12a = (a2 % 10);
a2 = a11a + a12a;
}
if (a4 >= 10) { // separating the digits of the multiple
int a31 = (a4 % 100) / 10;
int a32 = (a4 % 10);
a4 = a31 + a32;
}
if (a6 >= 10) { // separating the digits of the multiple
int a51 = (a6 % 100) / 10;
int a52 = (a6 % 10);
a6 = a51 + a52;
}
if (a8 >= 10) { // separating the digits of the multiple
int a71 = (a8 % 100) / 10;
int a72 = (a8 % 10);
a8 = a71 + a72;
}
if (a10 >= 10) { // separating the digits of the multiple
int a91 = (a10 % 100) / 10;
int a92 = (a10 % 10);
a10 = a91 + a92;
}
if (a12 >= 10) { // separating the digits of the multiple
int a111 = (a12 % 100) / 10;
int a112 = (a12 % 10);
a12 = a111 + a112;
}
if (a14 >= 10) { // separating the digits of the multiple
int a131 = (a14 % 100) / 10;
int a132 = (a14 % 10);
a14 = a131 + a132;
}
if (a16 >= 10) { // separating the digits of the multiple
int a151 = (a16 % 100) / 10;
int a152 = (a16 % 10);
a16 = a151 + a152;
}
int b = d1 + d3 + d5 + d7 + d9 + d11 + d13 + d15;
int c = a2 + a4 + a6 + a8 + a10 + a12 + a14 + a16;
int l = b + c;
int j = a2 + a4 + a6 + a8 + a10 + a12;
int k = d1 + d3 + d5 + d7 + d9 + d11 + d13;
int m = j + k;
int e = d1 + d3 + d5 + d7 + d9 + d11 + d13 + d15;
int x = a2 + a4 + a6 + a8 + a10 + a12 + a14;
int n = x + e;
printf("%i", n);
if (l % 10 == 0) { //checking if the checksum is valid
for (int i = number; number != 0; i++) { // counting the credit card number
number /= 10;
count++;
}
if (count == 16) {
if (last16m == 51) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16m == 52) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16m == 53) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16m == 54) { // checking the last two digit of credit card
printf("MASTERCARD\n"); //// printing the result based on last two digits
} else
if (last16m == 55) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16v == 4) { // checking the last two digit of credit card
printf("VISA\n"); // printing the result based on last two digits
} else {
printf("INVALID\n");
}
if (count != 16) {
printf("INVALID\n");
}
} else {
printf("INVALID\n");
}
}
if (m % 10 == 0) { //checking if the checksum is valid
for (int i = number; number != 0; i++) { // counting the credit card number
number /= 10;
count++;
}
if (count == 13) {
if (last13 == 4) { // checking the last one digit of credit card
printf("VISA\n"); // printing the result based on last one digit
} else {
printf("INVALID\n");
}
} else {
printf("INVALID\n");
}
}
if (n % 10 == 0) { //checking if the checksum is valid
for (int i = number; number != 0; i++) { // counting the credit card number
number /= 10;
count++;
}
if (count == 15) {
if (last15 == 34) { // checking the last two digit of credit card
printf("AMEX\n"); // printing the result based on last two digits
} else
if (last15 == 37) { // checking the last two digit of credit card
printf("AMEX\n"); // printing the result based on last two digits
} else {
printf("INVALID\n");
}
if (count != 15) {
printf("INVALID\n");
}
} else {
printf("INVALID\n");
}
}
}
我尝试使用 4003600000000014，它给出了正确的输出。取 4222222222222，它 returns INVALID。它也不适用于 AMEX 号码（15 位数字）。它不会响应 4111111111111113 作为输入（它应该 return 0）。请告诉我出了什么问题，我是编程新手。这是它通过 check50 https://submit.cs50.io/check50/44370b403c33f9b47d462e3278458901599d16e1.
检查时给出的结果
代码中存在多个问题：
number 的类型应该是 unsigned long long 以确保它足够大以处理 16 位数字。 unsigned long 在某些平台上可能足够大，例如 64 位 linux 和 OS/X，但在其他平台上则不够大，例如 Windows.
的所有版本
计算冗长繁琐，使用数字值数组可读性更好
不清楚您是计算 count 一次还是多次。循环修改 number 并且没有显式初始化 count （并且变量 i 没有用）。如果 运行 多次，它会巧合地工作，因为 number 从第一个 运行 开始已经是 0。您应该使用具有正确类型的临时变量并只计算一次 count。
不同卡号长度的测试可能会出现误报：例如如果m % 10 == 0且卡号不是13位数字，您将打印错误INVALID。测试应该首先是位数，然后是校验和。
将初始数字称为最后数字是非常令人困惑的。
这是一个使用数组的更简单的版本：
#include <stdio.h>
#include <stdlib.h>
// emulate cs50 get_long_long()
static long long get_long_long(const char *prompt) {
for (;;) {
long long n;
int c;
printf("%s", prompt);
if (scanf("%llu", &n) == 1)
return n;
printf("Invalid input, try again\n");
// flush the rest of the input line
while ((c = getchar()) != EOF && c != '\n')
continue;
if (c == EOF)
exit(1);
}
}
int main(void) {
long long int number, num;
int digit[16] = { 0 };
int count;
for (;;) { //getting input from the user
number = get_long_long("Please enter your 13-16 digit credit card number: \n");
if (number > 0)
break;
}
// only accept numbers with 13 to 16 digits
if (number < 1000000000000 || number > 9999999999999999) {
printf("INVALID\n");
return 1;
}
for (count = 0, num = number; num != 0; count++) {
digit[count] = num % 10;
num = num / 10;
}
// compute checksum
int checksum = 0;
for (int i = 0; i < 16; i += 2) {
int a1 = digit[i];
int a2 = digit[i + 1] * 2;
if (a2 >= 10)
a2 -= 9;
checksum += a1 + a2;
}
//printf("checksum: %d, ", checksum);
int first = digit[count - 1];
int first2 = 10 * digit[count - 1] + digit[count - 2];
if (checksum % 10 == 0) {
if (count == 16) {
if (first2 >= 51 && first2 <= 55) {
printf("MASTERCARD\n");
return 0;
} else
if (first == 4) {
printf("VISA\n");
return 0;
}
} else
if (count == 13) {
if (first == 4) {
printf("VISA\n");
return 0;
}
} else
if (count == 15) {
if (first2 == 34 || first2 == 37) {
printf("AMEX\n");
return 0;
}
}
}
printf("INVALID\n");
return 1;
}
#include <stdio.h>
#include <cs50.h>
#include <math.h>
int main(void) {
long int number;
int count = 0; // starting the count counter
do {
number = get_long("Please enter your 13-16 digit credit card number: \n"); //getting input from the user
} while (number <= 0);
int d1 = number % 10; //separating digit number 1
int d2 = ((number % 100) / 10); //separating digit number 2
int d3 = ((number % 1000) / 100); //separating digit number 3
int d4 = ((number % 10000) / 1000); //separating digit number 4
int d5 = ((number % 100000) / 10000); //separating digit number 5
int d6 = ((number % 1000000) / 100000); //separating digit number 6
int d7 = ((number % 10000000) / 1000000); //separating digit number 7
int d8 = ((number % 100000000) / 10000000); //separating digit number 8
int d9 = ((number % 1000000000) / 100000000); //separating digit number 9
int d10 = ((number % 10000000000) / 1000000000); //separating digit number 10
int d11 = ((number % 100000000000) / 10000000000); //separating digit number 11
int d12 = ((number % 1000000000000) / 100000000000); //separating digit number 12
int d13 = ((number % 10000000000000) / 1000000000000); //separating digit number 13
int d14 = ((number % 100000000000000) / 10000000000000); //separating digit number 14
int d15 = ((number % 1000000000000000) / 100000000000000); //separating digit number 15
int d16 = ((number % 10000000000000000) / 1000000000000000); //separating digit number 16
int last13 = number / 1000000000000; //finding the last one digit of 13 digit VISA
int last15 = number / 10000000000000; //finding the last two digit of 15 digit AMEX
int last16v = number / 1000000000000000; //finding the last one digit of 16 digit VISA
int last16m = number / 100000000000000; //finding the last two digit of 16 digit MASTERCARD
int a2 = (d2 * 2);
int a4 = (d4 * 2);
int a6 = (d6 * 2);
int a8 = (d8 * 2);
int a10 = (d10 * 2);
int a12 = (d12 * 2);
int a14 = (d14 * 2);
int a16 = (d16 * 2);
if (a2 >= 10) { // separating the digits of the multiple
int a11a = (a2 % 100) / 10;
int a12a = (a2 % 10);
a2 = a11a + a12a;
}
if (a4 >= 10) { // separating the digits of the multiple
int a31 = (a4 % 100) / 10;
int a32 = (a4 % 10);
a4 = a31 + a32;
}
if (a6 >= 10) { // separating the digits of the multiple
int a51 = (a6 % 100) / 10;
int a52 = (a6 % 10);
a6 = a51 + a52;
}
if (a8 >= 10) { // separating the digits of the multiple
int a71 = (a8 % 100) / 10;
int a72 = (a8 % 10);
a8 = a71 + a72;
}
if (a10 >= 10) { // separating the digits of the multiple
int a91 = (a10 % 100) / 10;
int a92 = (a10 % 10);
a10 = a91 + a92;
}
if (a12 >= 10) { // separating the digits of the multiple
int a111 = (a12 % 100) / 10;
int a112 = (a12 % 10);
a12 = a111 + a112;
}
if (a14 >= 10) { // separating the digits of the multiple
int a131 = (a14 % 100) / 10;
int a132 = (a14 % 10);
a14 = a131 + a132;
}
if (a16 >= 10) { // separating the digits of the multiple
int a151 = (a16 % 100) / 10;
int a152 = (a16 % 10);
a16 = a151 + a152;
}
int b = d1 + d3 + d5 + d7 + d9 + d11 + d13 + d15;
int c = a2 + a4 + a6 + a8 + a10 + a12 + a14 + a16;
int l = b + c;
int j = a2 + a4 + a6 + a8 + a10 + a12;
int k = d1 + d3 + d5 + d7 + d9 + d11 + d13;
int m = j + k;
int e = d1 + d3 + d5 + d7 + d9 + d11 + d13 + d15;
int x = a2 + a4 + a6 + a8 + a10 + a12 + a14;
int n = x + e;
printf("%i", n);
if (l % 10 == 0) { //checking if the checksum is valid
for (int i = number; number != 0; i++) { // counting the credit card number
number /= 10;
count++;
}
if (count == 16) {
if (last16m == 51) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16m == 52) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16m == 53) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16m == 54) { // checking the last two digit of credit card
printf("MASTERCARD\n"); //// printing the result based on last two digits
} else
if (last16m == 55) { // checking the last two digit of credit card
printf("MASTERCARD\n"); // printing the result based on last two digits
} else
if (last16v == 4) { // checking the last two digit of credit card
printf("VISA\n"); // printing the result based on last two digits
} else {
printf("INVALID\n");
}
if (count != 16) {
printf("INVALID\n");
}
} else {
printf("INVALID\n");
}
}
if (m % 10 == 0) { //checking if the checksum is valid
for (int i = number; number != 0; i++) { // counting the credit card number
number /= 10;
count++;
}
if (count == 13) {
if (last13 == 4) { // checking the last one digit of credit card
printf("VISA\n"); // printing the result based on last one digit
} else {
printf("INVALID\n");
}
} else {
printf("INVALID\n");
}
}
if (n % 10 == 0) { //checking if the checksum is valid
for (int i = number; number != 0; i++) { // counting the credit card number
number /= 10;
count++;
}
if (count == 15) {
if (last15 == 34) { // checking the last two digit of credit card
printf("AMEX\n"); // printing the result based on last two digits
} else
if (last15 == 37) { // checking the last two digit of credit card
printf("AMEX\n"); // printing the result based on last two digits
} else {
printf("INVALID\n");
}
if (count != 15) {
printf("INVALID\n");
}
} else {
printf("INVALID\n");
}
}
}
我尝试使用 4003600000000014，它给出了正确的输出。取 4222222222222，它 returns INVALID。它也不适用于 AMEX 号码（15 位数字）。它不会响应 4111111111111113 作为输入（它应该 return 0）。请告诉我出了什么问题，我是编程新手。这是它通过 check50 https://submit.cs50.io/check50/44370b403c33f9b47d462e3278458901599d16e1.
代码中存在多个问题：
的所有版本number的类型应该是unsigned long long以确保它足够大以处理 16 位数字。unsigned long在某些平台上可能足够大，例如 64 位 linux 和 OS/X，但在其他平台上则不够大，例如 Windows.计算冗长繁琐，使用数字值数组可读性更好
不清楚您是计算
count一次还是多次。循环修改number并且没有显式初始化count（并且变量i没有用）。如果 运行 多次，它会巧合地工作，因为number从第一个 运行 开始已经是0。您应该使用具有正确类型的临时变量并只计算一次count。不同卡号长度的测试可能会出现误报：例如如果
m % 10 == 0且卡号不是13位数字，您将打印错误INVALID。测试应该首先是位数，然后是校验和。将初始数字称为最后数字是非常令人困惑的。
这是一个使用数组的更简单的版本：
#include <stdio.h>
#include <stdlib.h>
// emulate cs50 get_long_long()
static long long get_long_long(const char *prompt) {
for (;;) {
long long n;
int c;
printf("%s", prompt);
if (scanf("%llu", &n) == 1)
return n;
printf("Invalid input, try again\n");
// flush the rest of the input line
while ((c = getchar()) != EOF && c != '\n')
continue;
if (c == EOF)
exit(1);
}
}
int main(void) {
long long int number, num;
int digit[16] = { 0 };
int count;
for (;;) { //getting input from the user
number = get_long_long("Please enter your 13-16 digit credit card number: \n");
if (number > 0)
break;
}
// only accept numbers with 13 to 16 digits
if (number < 1000000000000 || number > 9999999999999999) {
printf("INVALID\n");
return 1;
}
for (count = 0, num = number; num != 0; count++) {
digit[count] = num % 10;
num = num / 10;
}
// compute checksum
int checksum = 0;
for (int i = 0; i < 16; i += 2) {
int a1 = digit[i];
int a2 = digit[i + 1] * 2;
if (a2 >= 10)
a2 -= 9;
checksum += a1 + a2;
}
//printf("checksum: %d, ", checksum);
int first = digit[count - 1];
int first2 = 10 * digit[count - 1] + digit[count - 2];
if (checksum % 10 == 0) {
if (count == 16) {
if (first2 >= 51 && first2 <= 55) {
printf("MASTERCARD\n");
return 0;
} else
if (first == 4) {
printf("VISA\n");
return 0;
}
} else
if (count == 13) {
if (first == 4) {
printf("VISA\n");
return 0;
}
} else
if (count == 15) {
if (first2 == 34 || first2 == 37) {
printf("AMEX\n");
return 0;
}
}
}
printf("INVALID\n");
return 1;
}