为什么我的 c 程序在我的 if 语句中的条件为 true 后不打印我的错误消息？

问：

在我的程序中，我想检查用户输入的值是否会生成有效的表格，如果不是，我想打印错误消息。

我用了一个语句，后面跟着 .这适用于我的语句中除 和 条件之外的所有条件。当这些条件为真时，循环将中断，但不会打印错误消息。ifprintfif(upper <= 0)(upper <= kmlower)

这是我的代码：

/* Description: Program to calculate the flight time of an aeroplane,
 *              and tabulate it for a range of values of the distance
 *              travelled.
 *
 *==================================================================*/

/*==================================================================
 * Systems header files
 *==================================================================*/
#include <stdio.h>
#include <math.h>

/*==================================================================
 * Constant definitions
 *==================================================================*/
#define KMTOMILES 0.621371;
#define  AVGVELOCITY 529;

/*==================================================================
 * Function definitions
 *==================================================================*/

int main(void)
{
    /* Declaration of variables */
    int FlighttHours, intFlighttMin;
    float kmlower, upper, step /*km = lower */;
    float FlighttRem, miles, totalFlightt, floatFlighttMin;

    /* Interact with the user */
    printf("Enter the lower limit on distance in km:\t  ");
    scanf("%f", &kmlower);

    printf("Enter the upper limit on distance in km:\t  ");
    scanf("%f", &upper);

    printf("Enter the step size in km:\t\t\t  ");
    scanf("%f", &step);


    while (kmlower <= upper) /* Create output table */
    {
       ** **/* Check if the values input by the user will produce a valid table */
        if ((kmlower <= 0) || (upper <= 0) || (step <= 0) || (upper <= kmlower))
        {
            printf("\nERROR: these values will not  produce a valid output table\n");
            break;****
        }

        /* Continue loop if no errors */
        else
        {
            /* Print table headers once */
            printf("\n=================================================\n");
            printf("| distance (km) |     hours     |     minutes   |\n");
            printf("|===============================================|\n");

            /* Loop until upper limit is reached */
            while (kmlower <= upper)
            {
                /* Print range of distances */
                printf("|%10.2f\t|", kmlower);

                /* Calculate journey times */
                miles = kmlower * KMTOMILES;
                totalFlightt = miles / AVGVELOCITY;
                FlighttHours = (int)(totalFlightt);
                FlighttRem = totalFlightt - FlighttHours;
                floatFlighttMin = FlighttRem * 60;
                intFlighttMin = round(floatFlighttMin);

                /* Print results */
                printf("\t%d\t|\t%d\t|\n", FlighttHours, intFlighttMin );
                kmlower += step;
            }
        }
    }

    return (0);
}

当我运行代码和用户输入 or 时，会打印我的错误消息。kmlower <= 0step <= 0

结果 当 时，并显示错误消息：kmlower <= 0

Enter the lower limit on distance in km:         0
Enter the upper limit on distance in km:         4000
Enter the step size in km:                       500

ERROR: these values will not produce a valid output table

Process returned 0 (0x0)   execution time: 3.977 s
Press any key to continue.

结果 当 时，并显示错误消息：step <= 0

Enter the lower limit on distance in km:         500
Enter the upper limit on distance in km:         4000
Enter the step size in km:                       0

ERROR: these values will not produce a valid output table

Process returned 0 (0x0)   execution time: 7.016 s
Press any key to continue.

但是，当用户输入 或 时，代码会像我想要的那样停止，但不会打印错误消息。upper <= 0upper <= kmlower

结果时，无错误消息：upper <= 0

Enter the lower limit on distance in km:         500
Enter the upper limit on distance in km:         0
Enter the step size in km:                       200

Process returned 0 (0x0)   execution time: 14.927 s
Press any key to continue.

结果时，无错误消息：upper <= kmlower

Enter the lower limit on distance in km:         500
Enter the upper limit on distance in km:         400
Enter the step size in km:                       200

Process returned 0 (0x0)   execution time: 7.084 s
Press any key to continue.