我在此代码中的某个地方遇到了分段错误，但它已成功编译。代码是通过密钥重复迭代以加密明文字。我假设它与指针相关，但我不知道如何解决它。
另外：这是表达isalpha否定的合适方式吗？它没有抛出错误。当我尝试在它之后使用==FALSE时，它确实会抛出错误。
int main(int argc, char* argv[])
{
if ((argc<2) || (argc>2) || (!isalpha(argv)))//exits if non-alpha key or < or > than 2 command line inputs
{
printf("Please enter your single word key"); //prompts for appropriate key
return 1;
}
if(argc==2) // requires two command line inputs with non-integer key to continue
{
printf("plaintext:"); //Printed on terminal before word to be enciphered
char* word = GetString(); //Prompts user to enter word required to be enciphered
printf("ciphertext:");
char* key = (argv[1]); //key = initial user command line entry
int i = 0;
int k = 0; //defines characters in key
for(i=0; i<strlen(word); i++) //iterates through word entered by user as plaintext
{
if(isalpha(key[k]))
{
if(isupper(word[i])) //if original characters are uppercase
{
int cipher = (word[i] + key[k] -65) % 26 + 65;
printf("%c", cipher);
}
else if(islower(word[i])) //if original characters are lowercase
{
int cipher = (word[i] + key[k] - 97) % 26 + 97;
printf("%c", cipher);
}
else //for all other types of characters
{
printf("%c", word[i]);
}
}
else if(!isalpha(key[k]))
{
return 1;
}
if (word[i]==strlen(word)) //if reaches end of plaintext word
{
printf("\n"); //print a new line and exit
return 1;
}
else if(word[i]<strlen(word)) //if haven't reached end of word, increment k
{
k++;
}
if (key[k]==strlen(key))
{
k = 0;
}
}
printf("\n");
}
}