如何在C中使用setw和setfill来填充空格和字符？

Question

我需要为家庭作业编写一个程序来计算学费，输出的格式应该是这样的，在美元符号后加上点填充和空格填充：

Student Name:                Name goes here
Address:                     Address goes here


Number of credits: ..........         5
Cost per credit hour: ............ $ 50

到目前为止，我的代码是：

#include <iostream>
#include <iomanip>
#include <string>
#include <fstream>
using namespace std;

double const REG_FEE = 700, STUDENT_ASSEMBLY_FEE = 7.19, LEGAL_FEE = 8.50, STUDGOV_FEE = 1.50, 
LATE_FEE_PERCENTAGE = 0.015; 



int main()

{ double num_credits, cost_per_credit, tuition_total, late_charge, amount_due; 

string student_name;
string student_address; 
string student_city_state_ZIP;


ifstream info;
info.open ("info.txt");


getline (info, student_name);
getline (info, student_address);
getline (info, student_city_state_ZIP);
info >> num_credits;
info >> cost_per_credit;

tuition_total = num_credits * cost_per_credit + REG_FEE + STUDENT_ASSEMBLY_FEE + LEGAL_FEE
+ STUDGOV_FEE;
late_charge = tuition_total * LATE_FEE_PERCENTAGE;
amount_due = tuition_total + late_charge;


cout << "Tuition and Billing Program by Neal P." << endl
<< setw(18) << "Student Name:" << student_name << endl
<< setw(18) << "Address:" << student_address << endl
<< left << setfill('.') << endl
<< setfill(18) << "Number of Credits:" << setw(5) << "$" <<  num_credits << endl
<< setfill(18) << "Cost per Credit Hour:" << setw(5) << "$" << cost_per_credit << endl
<< setfill(18) << "Tuition Cost:" << setw(5) << "$" << tuition_total << endl
<< setfill(18) << "Registration Fee:" << setw(5) << "$" << REG_FEE << endl
<< setfill(18) << "MSA Fee:" << setw(5) << "$" << STUDENT_ASSEMBLY_FEE << endl
<< setfill(18) << "Legal Services Fee:" << setw(5) << "$" << LEGAL_FEE << endl
<< setfill(18) << "Student Government Fee:" << setw(5) << "$" << STUDGOV_FEE << endl;

return 0; 

}

当我编译时，我得到一个很长的错误，比如："在函数'int main（）'中： /Users/nealp/Desktop/machine问题2.cpp:41：错误：不匹配'运算符

Answer 1

只需在代码中替换set填充（18），这就是编译错误的原因。

这是经过改进的打印部分，以满足要求，

cout << "Tuition and Billing Program by Neal P." << endl
<< "Student Name:" << student_name << endl
<< "Address:" << student_address << endl
<<endl<<endl<< "Number of Credits:" << setfill('.') << setw(5) <<"$" <<  num_credits   
<< endl<< "Cost per Credit Hour:"<<setfill('.')<<setw(5)<< "$" << cost_per_credit << 
endl<< "Tuition Cost:" << setfill('.')<<setw(5)<< "$" << tuition_total << endl
<< "Registration Fee:" << setfill('.')<<setw(5) << "$" << REG_FEE << endl
<< "MSA Fee:" << setfill('.')<<setw(5) << "$" << STUDENT_ASSEMBLY_FEE << endl
<< "Legal Services Fee:" << setfill('.')<<setw(5) << "$" << LEGAL_FEE << endl
<< "Student Government Fee:" << setfill('.')<<setw(5) << "$" << STUDGOV_FEE << endl;

Answer 2

setfill是一个函数模板，它的模板参数是根据传递给它的参数类型推导出来的。它的返回类型是未指定的-它是一些实现定义的代理类型，用于在流对象上设置填充字符，并支持进一步链接操作符

literal的类型是int，所以setfill返回一些没有操作符的不相关类型

我不确定你所说的setfill（18）是什么意思，我猜你把它错当成了setw（18）。