检查 C 中字符串中的任何特殊字符

Question

I tried running this code and it seems that it will only check a characters and not a whole string, if I have a long string like "Adam@", does anyone know how to check like the whole string and not just a character like 'n'.

****char ch;
    /* Input character from user */
    printf("Enter any character: ");
    scanf("%c", &ch);
    /* Alphabet check */
    if((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))
    {
        printf("'%c' is alphabet.", ch);
    }
    else if(ch >= '0' && ch <= '9')
    {
        printf("'%c' is digit.", ch);
    }
    else 
    {
        printf("'%c' is special character.", ch);
    }****

Answer 1

scanf("%c", &ch);

This will only read a single character. To read an entire word, use:

char word[32]; // set size to the maximum word length you want to handle (+1 for null termination)
scanf("%31s", word);

Then use a loop to check every character in the word, such as:

for (int i = 0; i < 32; i++) {
    if (char[i] == 0) break;
    // Check word[i]
    ...
}

Answer 2

C language has no direct notion of string. Only the Standard Library has: by convention, a character string is represented as a null terminated character array.

So you must:

1. declare an array large enough the hold the expected strings (say no more than 31 characters)

    char word[32]; // 31 chars + 1 terminating null

2. read a (blank or space delimited) word taking care or not overflowing the array:

    scanf("%31s", word);

3. loop over the characters of that word:

    for (int i=0; i<strlen(word); i++) { char ch = word[i]; // copy here your current code processing ch }

Answer 3

As you would have to use a char array to store this string, you can easily iterate over this array.

Just like htis:

char s[100]; //string with max length 100
/* Input string from user */
printf("Enter any string: ");
scanf("%s", &s);
/* Alphabet check */
for(int i = 0; i <100; i++){
    char ch = s[i];
    if(ch == '\0') break; //stop iterating at end of string
     if((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))
    {
        printf("'%c' is alphabet.", ch);
    }
    else if(ch >= '0' && ch <= '9')
    {
        printf("'%c' is digit.", ch);
    }
    else 
    {
        printf("'%c' is special character.", ch);
    }
}