下面的程序用 C 语言执行凯撒密码。出于某种原因,在用户输入消息后, printf("\nEnter key:")
和
scanf("%d", &key)
语句被“跳过”。我的想法是与输入缓冲区有一个字符和换行符输入导致跳转有关(因此是 fflush
尝试)。我该如何防止这种行为?
#include <stdio.h>
#include <stdlib.h>
int main() {
char message[50], ms;
int i, key, choice;
printf("Enter 1. to Encrypt, or 2. to Decrypt: ");
scanf(" %d", &choice);
printf("Enter a message to process: ");
scanf(" %c", message);
printf(" \nEnter key:");
fflush(stdin);
scanf("%d", &key);
for (i = 0; message[i] != '\0'; ++i) {
ms = message[i];
if (ms >= 'a' && ms <= 'z' && choice == 1) {
ms = ms + key;
if (ms >= 'a' && ms <= 'z' && choice == 2) {
ms = ms - key;
if (ms > 'z') {
ms = ms - 'z' + 'a' - 1;
}
}
message[i] = ms;
} else
if (ms >= 'A' && ms <= 'Z' && choice == 1) {
ms = ms + key;
if (ms >= 'A' && ms <= 'Z' && choice == 2) {
ms = ms - key;
}
if (ms > 'Z') {
ms = ms - 'Z' + 'A' - 1;
}
message[i] = ms;
}
if (choice == 1) {
printf(" \nEncrypted message: %s", message);}
else if (choice == 2) {
printf(" \nDecrypted message: %s", message);}
}
}
最佳答案
@ddisec 我已经注意到3 mistakes
在您的代码中。
首先是你的scanf(" %c", message);
.这里你必须使用%s
(字符串)。
其次,结果打印语句应该在 for-loop
之外.
第三次推杆if(ms >= 'a' && ms <= 'z'&& choice == 2)
里面if (ms >= 'a' && ms <= 'z' && choice == 1)
没有任何意义。
试试这个更正后的代码:-
#include <stdio.h>
#include <stdlib.h>
int main()
{
char message[50], ms;
int i, key, choice;
printf("Enter 1. to Encrypt, or 2. to Decrypt: ");
scanf("%d", &choice);
getchar(); // to handle unwanted newline.
printf("Enter a message to process: ");
scanf("%49[^\n]", message);
printf(" \nEnter key:");
scanf("%d", &key);
for (i = 0; message[i] != '\0'; ++i)
{
ms = message[i];
if (ms >= 'a' && ms <= 'z' && choice == 1)
{
ms = ms + key;
}
else if (ms >= 'a' && ms <= 'z' && choice == 2)
{
ms = ms - key;
}
else if (ms > 'z')
{
ms = ms - 'z' + 'a' - 1;
}
else if (ms >= 'A' && ms <= 'Z' && choice == 1)
{
ms = ms + key;
}
else if (ms >= 'A' && ms <= 'Z' && choice == 2)
{
ms = ms - key;
}
else if (ms > 'Z')
{
ms = ms - 'Z' + 'A' - 1;
}
message[i] = ms; // Only single modification code needed.
}
if (choice == 1)
{
printf(" \nEncrypted message: %s", message);
}
else if (choice == 2)
{
printf(" \nDecrypted message: %s", message);
}
}
关于C 程序跳过 printf 和 scanf 语句,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/50555256/