如何在适用于 iPhone 的 iOS4 的 xcode 中将浮点数舍入为整数？

Question

可能的重复：
Objective-c：如何舍入浮动值？ < /p>

我知道它与 NSNumberformatter 类有关，请问有示例代码吗？

Answer 1

由于 int 无法存储浮点数，因此浮点数的小数部分将被截断，您将得到整个数字：

float x = 3.14159;
int y = (int)x;

这是有效的，因为 int只能存储整数，因此它只存储 x 的整数部分

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另请参阅 gnu C 库舍入功能：

 — Function: double ceil (double x)
 — Function: float ceilf (float x)
 — Function: long double ceill (long double x)
 — Function: double floor (double x)
 — Function: float floorf (float x)
 — Function: long double floorl (long double x)
 — Function: double trunc (double x)
 — Function: float truncf (float x)
 — Function: long double truncl (long double x)
 — Function: double rint (double x)
 — Function: float rintf (float x)
 — Function: long double rintl (long double x)
 — Function: double nearbyint (double x)
 — Function: float nearbyintf (float x)
 — Function: long double nearbyintl (long double x)
 — Function: double round (double x)
 — Function: float roundf (float x)
 — Function: long double roundl (long double x)
 — Function: long int lrint (double x)
 — Function: long int lrintf (float x)
 — Function: long int lrintl (long double x)
 — Function: long long int llrint (double x)
 — Function: long long int llrintf (float x)
 — Function: long long int llrintl (long double x)
 — Function: long int lround (double x)
 — Function: long int lroundf (float x)
 — Function: long int lroundl (long double x)
 — Function: long long int llround (double x)
 — Function: long long int llroundf (float x)
 — Function: long long int llroundl (long double x)
 — Function: double modf (double value, double *integer-part)
 — Function: float modff (float value, float *integer-part)
 — Function: long double modfl (long double value, long double *integer-part)

Answer 2

但如果将其转换为 int，3.999 也等于 3。

float value = 3.14159f;
int intValue = (int)value;
float fractional = fmodf(value, (float)intValue);
if(fractional > .5f)
    intValue++;

intValue 是您的舍入整数。