错误消息：如果数字不是整数而是浮点数

Question

为什么输入浮点数时不会出现错误？

int m;
if(scanf("%d%",&m)!=1)
{
    printf("Error\n");
    exit(1);
}

Answer 1

Answer 2

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h>

int str_int ( char *line, int *value)
{
    long int input = 0;
    char *end = NULL;//will point to end of parsed value

    if ( line == NULL) {
        return 0;
    }
    errno = 0;
    input = strtol ( line, &end, 10);//get the integer from the line. end will point to the end of the parsed value
    if ( end == line) {// nothing was parsed. no digits
        printf ( "input [%s] MUST be a number\n", line);
        return 0;// return failure
    }
    // *end is the character that end points to
    if ( *end != '\0') {// *end not '\0'
        printf ( "problem with input: [%s] \n", line);
        return 0;
    }
    if ( ( errno == ERANGE && ( input == LONG_MAX || input == LONG_MIN))
    || ( errno != 0 && input == 0)){// parsing error from strtol
        perror ( "input error");
        return 0;
    }

    if ( input < INT_MIN || input > INT_MAX) {
        printf ( "input: [%s] out of range %d %d\n", line, INT_MIN, INT_MAX);
        return 0;
    }

    if ( value == NULL) {
        return 0;
    }
    *value = input;// *value allows modification to callers int
    return 1;// success
}

int main( void)
{
    char line[100] = "";
    int number = 0;
    int valid = 0;

    do {
        printf ( "Enter number ( or quit)\n");
        if ( ! fgets ( line, sizeof line, stdin)) {//read a line
            fprintf ( stderr, "fgets EOF\n");
            return 1;//problem. exit program
        }
        if ( strcmp ( line, "quit\n") == 0) {
            return 0;// if quit is entered, exit the program
        }
        line[strcspn ( line, "\n")] = '\0';//remove newline

        valid = str_int ( line, &number);// call to parse a value

    } while ( !valid);// on failure, keep looping the above

    if ( valid) {
        printf ( "the number entered is %d\n", number);
    }

    return 0;
}