正常的float 轉換爲 int 的情況是採用去尾巴的方式,也就是說去掉小數點後面的數值。
1. 常規的float 轉換爲 int :
例如: 9.34 = (int) 9 ; 9.99 = (int) 9 。
#include<stdio.h>
int main()
{
float i = 9.34;
float j = 9.99;
int a, b;
a = (int) i;
b = (int) j;
printf("a = %d\n",a);
printf("b = %d\n",b);
}
上面的輸出結果爲:
a = 9
b = 9
2. float 轉換爲 int 需要四捨五入提高精度,則基本算法如下:
在計算是特別要注意正負數的問題,另外要注意round()函數轉換後雖然數值小數點後都變爲了零,但此時還是float,還需要轉換爲 int。
#include<stdio.h>
int main()
{
float zer = 0;
float i = 9.34;
float j = 9.99;
float k = -9.34;
float m = -9.99;
int a, b, c, d, e;
int a1, b1, c1, d1, e1;
a = (int) (i * 10 + 5) / 10;
b = (int) (j * 10 + 5) / 10;
c = (int) (k * 10 - 5) / 10;
d = (int) (m * 10 - 5) / 10;
e = zer;
a1 = (int) round(i)
b1 = (int) round(j);
c1 = (int) round(k);
d1 = (int) round(m);
e1 = (int) round(zer);
printf("a = %d\n",a);
printf("b = %d\n",b);
printf("c = %d\n",c);
printf("d = %d\n",d);
printf("e = %d\n",e);
printf("round a1 is %f\n", a1);
printf("round b1 is %f\n", b1);
printf("round c1 is %f\n", c1);
printf("round d1 is %f\n", d1);
printf("round e1 is %f\n", e1);
}
上面的輸出結果爲:
a = 9
b = 10
c = -9
d = -10
e = 0
round a1 is 9
round b1 is 10
round c1 is -9
round d1 is -10
round e1 is 0