[英]Printf() function acting strange
Apologies if this question is stupid, I'm new to coding, especially in C++. 抱歉,如果这个问题很愚蠢,我是编码新手,尤其是在C ++中。 I'm trying to read in data points from a space-separated text and then use the printf function to get it output them to the console.
我试图读取以空格分隔的文本中的数据点,然后使用printf函数将其输出到控制台。 When I try this;
当我尝试这个
#include<iostream>
#include<fstream>
#include<string>
using namespace std;
int main() {
double x[1000];
int i = 0;
int j;
double y[1000];
double sigmay[1000];
ifstream dataFile("xys_test.txt");
if (dataFile.is_open()) {
while (!dataFile.eof())
dataFile >> x[i] >> y[i] >> sigmay[i];
printf("x = %5.2f, y = %5.2f, sigmay = %5.2f\n", x[i], y[i], sigmay[i]);
i++;
}
}
All the console output gives me is the last data point, when I was hoping that all the points would be output into the console. 当我希望所有这些点都将输出到控制台中时,控制台输出给我的是最后一个数据点。 How can I resolve this?
我该如何解决?
You are missing a pair of { ... }
for the contents of your while
block. 您缺少
while
块内容的一对{ ... }
。 Currently, only the dataFile >> x[i] >> y[i] >> sigmay[i];
当前,只有
dataFile >> x[i] >> y[i] >> sigmay[i];
line is inside the while
block. 行在
while
块内。
if (dataFile.is_open()) {
while (!dataFile.eof()) {
dataFile >> x[i] >> y[i] >> sigmay[i];
printf("x = %5.2f, y = %5.2f, sigmay = %5.2f\n", x[i], y[i], sigmay[i]);
i++;
}
}
you lost your curly bracket, 你失去了花括号,
while (!dataFile.eof()) {
dataFile >> x[i] >> y[i] >> sigmay[i];
printf("x = %5.2f, y = %5.2f, sigmay = %5.2f\n", x[i], y[i], sigmay[i]);
i++;
}
The code should be: 代码应为:
while ( i < 1000 && (dataFile >> x[i] >> y[i] >> sigmay[i]) )
{
printf("x = %5.2f, y = %5.2f, sigmay = %5.2f\n", x[i], y[i], sigmay[i]);
++i;
}
You should test whether or not the read operation succeeded, in order to decide whether to proceed with printing and committing the data. 您应该测试读取操作是否成功,以便决定是否继续打印和提交数据。 Testing eof is irrelevant and a mistake.
测试eof无关紧要并且是错误的。
Also #include <cstdio>
should be used for printf
. 同样,
#include <cstdio>
也应用于printf
。 Possibly your compiler/library setup involves cstdio being included by iostream but in general that is not the case. 可能是您的编译器/库设置涉及iostream包含cstdio,但通常情况并非如此。
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