C-舍入问题(CS50) [英] C - Rounding issues (CS50)

问题描述

我已经在谷歌上搜索了好几天了，我迷路了.因此，在线进行CS50似乎无法解决这一数字舍入问题.我的程序搞砸了将 2.10 之类的浮点数与 100 之类的整数相乘，它会输出 209.xxxxxxxx

I have been Googling this for days now and I am lost. So doing CS50 online and can't seem to get a handle on this rounding of numbers. My program is messing up multiplying floats like 2.10 with integers like 100 it would output 209.xxxxxxxx

现在，就像我说我已经阅读了许多关于应该使用 ceilf 并包含 的帖子一样，但是我遇到了错误

Now like I say I have read countless posts on that I should use ceilf and include but I am getting an error

greedy.c :(.text + 0x74):对'ceilf'的未定义引用 collect2:错误:ld返回1退出状态make:*** [贪婪]错误1 亚当@贝多芬:〜/projects/atom/edx/pSet1/greedy $

greedy.c:(.text+0x74): undefined reference to `ceilf' collect2: error: ld returned 1 exit status make: *** [greedy] Error 1 adam@beethoven:~/projects/atom/edx/pSet1/greedy$

我看过有关-lm和某个文件的帖子，但是老实说我不明白这是什么意思.

I have seen the posts about -lm and a certain file but if I am honest I don't understand what it means.

我绝不是在寻找一种彻底的解决方案，而只是寻求改进的指导.

I am in no way looking for an outright solution, just guidance in improving.

这是我的代码，可能不像某些人希望的那样精简，但我在这里回到了基础；)

Here is my code, probably not as streamlined as some would like but I am back to basics here ;)

#include <stdio.h>
#include <math.h>

int main() {
  // Initialize Variables
  int coinsTotal = 0,
      quarter = 25,
      dime = 10,
      nickel = 5,
      penny = 1,
      cents;
  float changeDue;

  do {
    printf("How much change are you owed? (Format = 0.00)($): ");
    scanf("%f", &changeDue );
    // Convert to cents
    cents = changeDue * 100;
  } while(cents <= 0);

  while (cents >= quarter) {
    cents = cents - quarter;
    coinsTotal = coinsTotal + 1;
  } if (cents == 0) {
      printf("The miminum number of coins is: %d\n", coinsTotal);
  } else {
      while (cents >= dime) {
        cents - dime;
        coinsTotal = coinsTotal + 1;
      } if (cents == 0) {
          printf("The minimum number of coins is: %d\n", coinsTotal);
      } else {
          while (cents >= nickel) {
            cents = cents - nickel;
            coinsTotal = coinsTotal + 1;
          } if (cents == 0) {
              printf("The minimum number of coins is: %d\n", coinsTotal);
          } else {
              while (cents >= penny) {
                cents = cents - penny;
                coinsTotal = coinsTotal + 1;
              } if (cents == 0) {
                  printf("The minimum number of coins is: %d\n", coinsTotal);
                }
        }
      }
    }
}

基本上，它应该计算出一定数量所需的最少硬币数量.在大多数情况下，它会起作用，直到浮子弄乱为止.打扰一下我喜欢写的笔记，这样我会学得更好.

Basically it should work out the minimum number of coins needed to make a given amount. It works in most cases until the floats mess up. Excuse the notes I like to write what I did so I learn better.

Update尝试使用-lm与GCC进行编译，但仍然失败. 亚当@贝多芬:〜/projects/atom/edx/pSet1/greedy $ gcc -o foo -lm greedy.c/tmp/cc3qHAK7.o:在函数main': greedy.c:(.text+0x6e): undefined reference to ceilf'collect2中:错误:ld返回1退出 状态adam @ beethoven:〜/projects/atom/edx/pSet1/greedy $

Update Tried to compile with GCC using -lm but still failed. adam@beethoven:~/projects/atom/edx/pSet1/greedy$ gcc -o foo -lm greedy.c /tmp/cc3qHAK7.o: In function main': greedy.c:(.text+0x6e): undefined reference toceilf' collect2: error: ld returned 1 exit status adam@beethoven:~/projects/atom/edx/pSet1/greedy$

解决方案我没有使用 make 命令，而是使用了gcc并添加了 -lm标志在命令末尾 gcc -o foo greedy.c -lm

SOLUTION Instead of using the make command I used gcc and added the -lm flag At the end of the command gcc -o foo greedy.c -lm

推荐答案

我看过有关-lm和某个文件的帖子，但是老实说我不明白这是什么意思.

I have seen the posts about -lm and a certain file but if I am honest I don't understand what it means.

您必须链接到数学库以纠正错误.数学函数的实现通常放在一个单独的库中，即数学库.如果使用gcc，请在链接器命令中添加-lm.

You have to link to the math library to fix the error. Math functions implementations are usually put as a separate library, the math library. If you use gcc add -lm to the linker command.

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