c函数实用函数

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我有一个疑问，Class类对象是在main函数之前的dyld阶段加载进内存的，那它是在内存的静态区还是堆区存储着？

好了，疑问先放着，我们进入正题，在iOS开发中我们经常遇到 浮点数的 四舍五入、进位、摸位 方法。

我们可以通过速查表查看所有的C函数，https://baike.baidu.com/item/Objective-C函数速查实例手册?fr=aladdin

这里列出常用的几个函数：
1，四舍五入法
float numberToRound;

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int result;

numberToRound = 5.61;

result = (int)roundf(numberToRound);

NSLog(@"roundf(%.2f) = %d", numberToRound, result);

// 输出 roundf(5.61) = 6



numberToRound = 5.41;

result = (int)roundf(numberToRound);

NSLog(@"roundf(%.2f) = %d", numberToRound, result);

// 输出 roundf(5.41) = 5

2、进位方法
float numberToRound;
int result; 

numberToRound = 5.61;

result = (int)ceilf(numberToRound);

NSLog(@"ceilf(%.2f) = %d", numberToRound, result);

// 输出 ceilf(5.61) = 6



numberToRound = 5.41;

result = (int)ceilf(numberToRound);

NSLog(@"ceilf(%.2f) = %d", numberToRound, result);

// 输出 ceilf(5.41) = 6

3、摸位方法
float numberToRound;

int result;

numberToRound = 5.61;

result = (int)floorf(numberToRound);

NSLog(@"floorf(%.2f) = %d", numberToRound, result);

// 输出 floorf(5.61) = 5



numberToRound = 5.41;

result = (int)floorf(numberToRound);

NSLog(@"floorf(%.2f) = %d", numberToRound, result);

// 输出 floorf(5.41) = 5