c - 声明的变量未显示在调试器的局部变量中

Question

这是一个计算行长度的简单程序。程序的所有计算方面都已完成并正在运行。但我在一个非常简单的方面遇到了麻烦，变量“percent_detoured”在第 10 行声明并在第 83 行使用，并在第 84 行打印。问题是执行时，其他一切都运行良好，但 percent_detoured 始终返回 0.000。调试时，percent_detoured 甚至不会在“Locals”中显示为变量。如果有帮助的话，我正在使用 Pelles C IDE。

感谢您的帮助!

{
float line_value;       
int x_1, y_1, x_2, y_2;         
float y_intercept;      
float distance, greatest_distance, total;
float percent_detoured;             // <-- DECLARED HERE (SCROLL ALL THE WAY DOWN TO SEE WHERE IT IS USED)
int count, detour_count;        

x_1=1; y_1=1; x_2=1; y_2=1;     
greatest_distance = 0;  total = 0;  count = 0;  detour_count = 0; 

/* Ask for user input in setting the coordinates of the line */
printf("Enter in the length of the line\n");
scanf("%f", &line_value);


/* If user enters in y coordinates for the line such that the line length is greater
    than 10 units, then enter loop and continue looping until the length is smaller or 
    equal to 10 */
while ( line_value > 10 || line_value < 0)
{
    printf("Try Again. Value should be smaller or equal to 10 units\n");
    scanf("%f", &line_value);
}

line_value = line_value / 2;            //Define the top of the line

printf("Enter x and y coordinates for point 1 and 2\n");
scanf("%d %d %d %d", &x_1, &y_1, &x_2, &y_2);

if ( x_1 == 0 && x_2 == 0 && y_1 == 0 && y_2 == 0 )     //If user enters in 0 0 0 0 right away, then immediately end the program
{
    printf("No path lengths have been calculated\n");
}

else        
{
    /* While the user does not enter in the values 0 0 0 0 for all coordinates, continue while loop */
    while ( (x_1 != 0) || (y_1 != 0) || (x_2 != 0) || (y_2 != 0) )
    {
        y_intercept = y_1 - ( (y_2 - y_1) / (x_2 - x_1) * x_1 );    //Rearrange (y=mx+b) to get (b=y-mx) where b is the y intercept

        if ( y_intercept <= line_value && y_intercept >= 0 )    //If the y-intercept of the line from point a to b is between
        {                                                           //the top of L and 0, then calculate distance between a and top of L
            distance = sqrt( pow(x_1, 2) + pow((y_1 - line_value), 2) )
                        + sqrt( pow(x_2, 2) + pow((line_value - y_2), 2) );
            detour_count++;                 //Updating the detour counter
        }
        else if ( y_intercept >= ( line_value * -1) && y_intercept < 0 )    //If the y-intercept of the line from point a to b is between 
        {                                                                   //the bottom of L and 0, then calculate distance between a and bottom of L
            distance = sqrt( pow(x_1, 2) + pow( (y_1 + line_value), 2) )
                        + sqrt( pow(x_2, 2) + pow(( y_2 - (line_value * -1) ), 2) );
            detour_count++;                 //Updating the detour counter
        }
        else 
        {
            distance = sqrt( pow((x_2 - x_1), 2) + pow((y_2 - y_1), 2));    //If shortest path between point a and b does not cross L,
        }                                                                   //then the distance is just the sum of squares of rise and run

        if (distance > greatest_distance)
        {
            greatest_distance = distance;   //If the current distance is greater than the previous, set it as the greatest distance
        }

        total = total + distance;       //Total count of distance
        count++;                        //Update general counter

        printf("The shortest path is: %f\n", distance);

        printf("Enter x and y coordinates for point 1 and 2\n");
        scanf("%d %d %d %d", &x_1, &y_1, &x_2, &y_2);
    }

}

printf("\nThe average path length: %f\n", (total/count));       
printf("The length of the longest path: %f\n", greatest_distance);

percent_detoured = ((detour_count/count) * 100);        // <-- USED IT HERE
printf("The percentage of paths involving a detour: %f\n", percent_detoured );    // <-- SHOULD BE PRINTED AS ITS VALUE HERE

return 0;

}

Answer 1

你应该使用

percent_detoured = ((float)detour_count/count) * 100.0);

否则，detour_count 和 count 都是整数，int 除以 int 会得到一个 int。因此，假设 detour_count < count，detour_count/count 将四舍五入为 0，乘​​以 100(仍然为 0)，最后四舍五入为 float ，因为它存储为 float (percent_detoured)。

我从未使用过你提到的 IDE，所以我不知道为什么它可能没有显示在调试器中。 :)