C++ 如何编写一个for循环来计算C中各项的总和

我正在编写一项作业(job)，要求我做以下工作:

1. User input:十进制数字列表.(这些项目代表美元的数值，第一项是美元兑换比率，

(比方说1usd = 3.58another_currency个.)

2. 将值转换为另一种货币(转换后的项目将以another list为单位)

2.1例如: 原文:[3.58 12 11.50 3.20 4.10] -> 转换:[(42.96)，(41.17)，.] (multiplied 3.58 by each item next)

3. 以漂亮的表格形式显示它，表格的最后一行应该是the sum of the dollars和the sum of the converted currency

It seems that I have done the first step, and the second step correctly. But when calculating the sum of the other currency, I ran into a problem. Only the sum of the dollars happen to be correct, but the sum of the other currency is problematic. Not only it's incorrect, the sum is changing every time I run it. Green one is correct, red one is not correct.

我激活了same function upon the two different arrays，但它只正确计算了其中的一个和.

MY .H文件(doll.c):

#define SIZE 10

void dollar_to_shekel(float[], float[]);

void print_array(float[], float[]);

float sum_array(int, float[]);

我的.c文件(doll.c):

#include <stdio.h>
#include "doll.h"

void dollar_to_shekel(float usd[], float ils[])
{
  int i;
  for(i=1; i<SIZE; i++)
  {
    /*the first element in the received list, in index 0, is the dollar ratio*/
    ils[i-1] = usd[i] * usd[0];
  }
}

void print_array(float usd[], float ils[])
{
  int i;
  for(i=1; i<SIZE; i++)
  {
    printf("%.2f \t \t \t \t %.2f\n", usd[i], ils[i-1]);
  }
}

float sum_array(int x, float arr[])
{
  int i;
  float sum = 0;
  for(i=x; i<SIZE; i++)
  {
    sum = sum + arr[i];
  }
  return sum;
}

int main()
{
  float usd[SIZE];
  float ils[SIZE];
  int i;
  printf("Insert a list of numbers:");
  for(i=0; i<SIZE; i++)
  {
    scanf("%f", &usd[i]);
  }

  dollar_to_shekel(usd, ils);
  printf("$ \t \t \t \t IS\n");
  print_array(usd,ils);
  printf("%.2f \t \t \t \t %.2f\n", sum_array(1,usd), sum_array(0,ils));

  return 0;
}

我真的不知道程序在哪里以及为什么在计算一列的总和时失败，但在另一列上做了这项工作.