我是C语言的新手，编写这个程序只是为了好玩。但后来我遇到了一个问题。每次system("cls")出现时，encryptedWord似乎都会擦除它的值。事情应该是那样的吗?如果是这样，你有什么替代的建议吗?
下面是我的代码:
const char * dencrypt(int numeric, const char * encryptedWord);
int getKey();
void displayKey(int number, char *keyUp, char *keyLow, int num, char *keys);
int main(void) {
int ans = 'y';
int choice;
const char * encryptedWord = " ";
int count = 1;
while (ans == 'y' || ans == 'Y') {
system("cls");
printf("This program will encrypt and decrypt message accordingn");
printf("to your choice.nn");
puts ("Pick your choice..");
puts ("1. Encrypt");
puts ("2. Decrypt");
printf("n");
printf("Enter choice: ");
scanf("%d", &choice);
getchar();
while (choice < 1 || choice > 2) {
puts("Sorry kid, only 1 or 2.");
printf("Enter choice: ");
scanf("%d", &choice);
getchar();
}
switch(choice) {
case 1:
system("cls");
encryptedWord = dencrypt(choice, encryptedWord);
break;
case 2:
if (count > 1) {
system("cls");
printf("nDo you want to use your last encrypted word?n");
printf("Note that if you pick NO, your encrypted wordnwill be erased from the memory..");
printf("n1. YES");
printf("n2. NO");
printf("nInput choice: ");
scanf("%d", &choice);
getchar();
system ("cls");
while(choice < 1 || choice > 2) {
printf("nPfft.. pick only 1 or 2.");
printf("nInput choice: ");
scanf("%d", &choice);
getchar();
}
switch (choice) {
case 1:
printf("nLast Encrypted Word: %sn", encryptedWord);
break;
case 2:
break;
}
} else {
system("cls");
}
dencrypt(choice, encryptedWord);
break;
}
printf("nnDo you want to continue?n");
printf("Note that in doing so the console will be cleared");
printf("nPress Y to continue or any other key to end this program.n");
ans = getchar();
getchar();
count++;
}
}
const char * dencrypt(int numeric, const char * rWord) {
int keyStr, num,i, s, total;
int c;
bool found;
char word[SIZE];
char fWord[SIZE];
char keyUp[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
char keyLow[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
char keys[25];
switch (numeric) {
case 1:
puts("Input key for encryption");
break;
case 2:
puts("Input key for decryption");
break;
}
num = getKey() - 'A';
displayKey(numeric , keyUp, keyLow, num, keys);
printf("nn");
switch(numeric) {
case 1:
puts("Input a word to be encrypted");
break;
case 2:
puts("Input a word to be decrypted");
break;
}
i = 0;
total = 0;
while(i < SIZE - 1 && (c = getchar()) != 'n') {
word[i++] = c;
total++;
}
word[i] = ' ';
printf("n");
puts("Original Word: ");
printf("%snn", word);
switch(numeric) {
case 1:
printf("Encrypted word: n");
for (i = 0; i <= total - 1; i++) {
found = false;
s = 0;
if (islower(word[i])) {
while (found != true) {
if (word[i] == keyLow[s]) {
found = true;
} else {
s++;
}
}
s += num;
if (s > 25) {
s -= 26;
}
printf("%c", keyLow[s]);
fWord[i] = keyLow[s];
} else if (isupper(word[i])) {
while (found != true) {
if (word[i] == keyUp[s]) {
found = true;
} else {
s++;
}
}
s += num;
if (s > 25) {
s -= 26;
}
printf("%c", keyUp[s]);
fWord[i] = keyUp[s];
} else if(isspace(word[i])) {
printf(" ");
fWord[i] = ' ';
} else {
printf("%c", word[i]);
fWord[i] = word[i];
}
}
printf("nnn");
rWord = fWord;
break;
case 2:
printf("Decrypted word: n");
for (i = 0; i <= total - 1; i++) {
found = false;
s = 0;
if (islower(word[i])) {
while (found != true) {
if (word[i] == keyLow[s]) {
found = true;
} else {
s++;
}
}
s -= num;
if (s < 0) {
s += 26;
}
printf("%c", keyLow[s]);
} else if (isupper(word[i])) {
while (found != true) {
if (word[i] == keyUp[s]) {
found = true;
} else {
s++;
}
}
s -= num;
if (s < 0 ) {
s += 26;
}
printf("%c", keyUp[s]);
} else if(isspace(word[i])) {
printf(" ");
} else {
printf("%c", word[i]);
}
}
printf("nnn");
break;
}
return rWord;
}
你没有发布dencrypt()的代码，但我的精神力量告诉我这就是错误所在:这个函数返回本地缓冲区的地址(一个大的禁忌)，它被后续的函数调用覆盖。
您需要在返回缓冲区之前动态分配缓冲区，或者在main()中分配它并将其作为参数传递给dencrypt()。