scanf(“%c”) automatically reads 10

问题

void main() 
{ 
    int cnt=1; 
    char i; 
    while(cnt<4) 
    {
        printf("\nenter the character"); 
        scanf("%c",&i); 
        if(i>64 && i<91) 
            printf("\ncharacter is entered"); 
        else 
            printf("\nnumber is entered"); 
        cnt++; 
    }
}

In the above program, during the second iteration, i automatically takes 10. So the control goes to else part. Can anyone help me find what is the issue?

回答1:

In the first iteration, you type a character and press Enter. scanf consumes the character you entered, leaving the \n in the standard input stream (stdin).

In the second iteration, scanf sees the \n character consumes it, thus not waiting for further input.

You can tell scanf to read and discard the next character by using:

scanf("%c%*c", &i);

or you can tell scanf to read and discard all whitespace characters, if any, before reading a character and storing it in i by using:

scanf(" %c",&i);
/*     ↑ Note the space */

来源：https://stackoverflow.com/questions/35110942/scanfc-automatically-reads-10