分配+零個

Question

好傢伙我有這樣的代碼：

#include <stdio.h> 
#include <stdlib.h> 

int main() 
{ 
    int x1,y1,x2,y2,x3,y3; 
    float a,b,a2,b2,xf3,yf3,xa,ya; 

    printf("please find the line1 formula: y = ax+b\n"); 
    printf("please input any point (x1,y1):\n"); 
    printf("input x1:"); 
    scanf("%d",&x1); 
    printf("input y1:"); 
    scanf("%d",&y1); 

    printf("please input any point (x2,y2):\n"); 
    printf("input x2:"); 
    scanf("%d",&x2); 
    printf("input y2:"); 
    scanf("%d",&y2); 

    a=(y2-y1)/(x2-x1); 
    b=y1-(a*x1); 
    b=(b); 

    printf("this formula: y = %fx %f\n\n",a,b); 
    printf("please input any point(x3,y3):\n"); 
    printf("input x3:"); 
    scanf("%d",&x3); 
    printf("input y3:"); 
    scanf("%d",&y3); 

    xf3=x3; 
    yf3=y3; 

    a2 = -1/a; 
    b2=y3-(a2*x3); 
    xa=(b2-b)/(a-a2); 
    ya=a2*xa+b2; 
    printf("the line2 which contains (%.3f,%.3f) perpendicular to the line1.",xf3,yf3); 
    printf("please find the intersection point of line1 and line2: \n"); 
    printf("(%f,%f) ",xa,ya); 



    return 0; 
} 

它的工作原理，但打印第一線時，我有一個問題。 我應該將其打印爲y=ax+b。如果b是正數或負數，那麼就沒有問題了。但是，如果b爲零，則會打印（示例）y=2.000000x0.000000我需要它爲y=2.000000x+0.000000。

我該如何解決這個問題？

Answer 1

格式字符串%+f可能適用於您的情況。否則，您可以簡單地打印一個字符，即b < 0 ? '-' : '+'。