# [IOS 四舍五入 进一法 去尾法]

原文来自：(https://www.cnblogs.com/yujidewu/p/5724966.html)

float numberToRound;

int result;

numberToRound = 4.51;

result = (int)roundf(numberToRound);

NSLog(@"roundf(%f) = %d", numberToRound, result); // roundf(4.510000) = 5

result = (int)ceilf(numberToRound);

NSLog(@"ceilf(%f) = %d", numberToRound, result); // ceilf(4.510000) = 5

result = (int)floorf(numberToRound);

NSLog(@"floorf(%f) = %d", numberToRound, result); // floorf(4.510000) = 4

numberToRound = 10.49;

result = (int)roundf(numberToRound);

NSLog(@"roundf(%f) = %d", numberToRound, result); // roundf(10.490000) = 10

result = (int)ceilf(numberToRound);

NSLog(@"ceilf(%f) = %d", numberToRound, result); // ceilf(10.490000) = 11

result = (int)floorf(numberToRound);

NSLog(@"floorf(%f) = %d", numberToRound, result); // floorf(10.490000) = 10

numberToRound = -2.49;

result = (int)roundf(numberToRound);

NSLog(@"roundf(%f) = %d", numberToRound, result); // roundf(-2.490000) = -2

result = (int)ceilf(numberToRound);

NSLog(@"ceilf(%f) = %d", numberToRound, result); // ceilf(-2.490000) = -2

result = (int)floorf(numberToRound);

NSLog(@"floorf(%f) = %d", numberToRound, result); // floorf(-2.490000) = -3

numberToRound = -3.51;

result = (int)roundf(numberToRound);

NSLog(@"roundf(%f) = %d", numberToRound, result); // roundf(-3.510000) = -4

result = (int)ceilf(numberToRound);

NSLog(@"ceilf(%f) = %d", numberToRound, result); // ceilf(-3.510000) = -3

result = (int)floorf(numberToRound);

NSLog(@"floorf(%f) = %d", numberToRound, result); // floorf(-3.510000) = -4