我正在为我的程序编写一个函数,该函数从文本文件中读取名字和姓氏并将它们保存为两个字符串。但是,当for循环到达名字和姓氏之间的第一个空格时,我无法执行if(isspace(next))语句。
这是完整的程序
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
#include <ctype.h>
using namespace std;
void calcAvg(ifstream& in, ofstream& out);
int main()
{
//open input and output file streams and check for any failures
ifstream input;
ofstream output;
input.open("lab08_in.txt");
output.open("lab08_out.txt");
if(input.fail())
{
cout << "Error: File not Found!" << endl;
exit(1);
}
if(output.fail())
{
cout << "Error: File creation failed!" << endl;
exit(1);
}
calcAvg(input, output);
return 0;
}
void calcAvg(ifstream& in, ofstream& out)
{
int sum = 0;
double average;
//save first and last name to strings
string firstname, lastname;
char next;
int i = 1;
in >> next;
for(; isalpha(next) && i < 3; in >> next)
{
if(i == 1)
{
firstname += next;
cout << next << " was added to firstname" << endl;
if(isspace(next))
{
cout << "Space!" << endl;
out << firstname << ' ';
i++;
}
}
else if(i == 2)
{
lastname += next;
cout << next << " was added to lastname" << endl;
if(isspace(next))
{
cout << "Space!" << endl;
out << lastname << ' ';
i++;
}
}
}
}
我遇到麻烦的代码部分是
if(isspace(next))
{
cout << "Space!" << endl;
out << firstname << ' ';
i++;
}
代码应该(在我看来)从文件中读取每个字符并添加到字符串中,一旦到达空格,则将该字符串名写入输出文件,但是没有,相反,我在控制台中获得了此输出
H was added to firstname
e was added to firstname
s was added to firstname
s was added to firstname
D was added to firstname
a was added to firstname
m was added to firstname
等等...
请注意,该名称应该是Hess Dam ....,应该发生的是它将Hess保存为firstname,将Dam ....保存为lastname。相反,它只是将整个内容添加到名字字符串中姓氏后面的制表符之前,并且永远不会写入输出文件。它读取选项卡,因为它退出for循环(从isalpha(next)开始),但由于某些原因,isspace(next)参数不起作用
最佳答案
抱歉,没有足够的信誉来发表评论,但是有两个错误的答案。扎希尔的评论是正确的。 std::isspace(c,is.getloc())对于in中的下一个字符c为true(此空白字符保留在输入流中)。运算符>>绝不会返回空格。