Question

所以我早些时候来到这里询问有关从文件中读取每个字符的学校作业。这个问题已得到解决，但现在我遇到了另一个问题。我的部分工作是接受用户输入的文件名，然后将该文件名设置为将与程序结果一起输出的文本文件。这是程序本身：

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

int main()
{
    const int fileNameSize = 20;
    int fileCount = 0;
    int testcount = 0;
    const string outName;
    std::ifstream inFile;
    std::ofstream outFile;
    <a bunch of other stuff>
            outFile.open(outName);
            int chartotal = acount + tcount + ecount + ocount + icount + ncount + scount + hcount + rcount;
            outFile << "File name: " << inputFileName << endl;
            outFile << "Number of E's: " << ecount << endl;
            outFile << "Number of T's: " << tcount << endl;
            outFile << "Number of A's: " << acount << endl;
            outFile << "Number of O's: " << ocount << endl;
            outFile << "Number of I's: " << icount << endl;
            outFile << "Number of N's: " << ncount << endl;
            outFile << "Number of S's: " << scount << endl;
            outFile << "Number of H's: " << hcount << endl;
            outFile << "Number of R's: " << rcount << endl;
            outFile << "Total Number of Characters: " << chartotal << endl;
            outFile << "--------------------------------" << endl;
            outFile.close();
            return 0;
        }
        inFile.close();
        inFile.clear();
    }
    //cout << "exit colm flag";
    //cout << "exit row flag\n";

}

我的理解是outFile.open(outName);应该创建一个文件名设置为outName的新文件，但是每次编译时我都会遇到很长的错误。我做错了什么？

编辑：这是我收到的错误

closed4Ahrens.cpp: In function 'int main()':
closed4Ahrens.cpp:19:9: error: no match for 'operator>>' in 'std::cin >> outName'
closed4Ahrens.cpp:19:9: note: candidates are:
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:122:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:122:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&) {aka std::basic_istream<char>& (*)(std::basic_istream<char>&)}'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:126:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>, std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:126:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:133:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:133:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'std::ios_base& (*)(std::ios_base&)'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:169:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:169:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'bool&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:173:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char, _Traits = std::char_traits<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:173:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'short int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:176:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:176:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'short unsigned int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:180:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char, _Traits = std::char_traits<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:180:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:183:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:183:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'unsigned int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:187:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:187:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'long int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:191:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:191:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'long unsigned int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:196:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:196:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'long long int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:200:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:200:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'long long unsigned int&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:205:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:205:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'float&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:209:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:209:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'double&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:213:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:213:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'long double&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:217:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:217:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'void*&'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:241:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:241:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'std::basic_istream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}'
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/bits/basic_string.tcc:998:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::basic_string<_CharT, _Traits, _Alloc>&)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/bits/istream.tcc:957:5: note: template<class _CharT2, class _Traits2> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT2*)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/bits/istream.tcc:925:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:709:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char&)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:714:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char&)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:756:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/istream:761:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/iomanip:70:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::_Resetiosflags)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/iomanip:100:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::_Setiosflags)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/iomanip:131:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::_Setbase)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/iomanip:169:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::_Setfill<_CharT>)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/iomanip:199:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::_Setprecision)
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/iomanip:229:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::_Setw)
closed4Ahrens.cpp:68:24: error: no matching function for call to 'std::basic_ofstream<char>::open(const string&)'
closed4Ahrens.cpp:68:24: note: candidate is:
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/fstream:702:7: note: void std::basic_ofstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char, _Traits = std::char_traits<char>, std::ios_base::openmode = std::_Ios_Openmode]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/fstream:702:7: note:   no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'const char*'

更新：我删除了const中的const string outName，现在错误消息要短得多

closed4Ahrens.cpp:68:24: error: no matching function for call to 'std::basic_ofstream<char>::open(std::string&)'
closed4Ahrens.cpp:68:24: note: candidate is:
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/fstream:702:7: note: void std::basic_ofstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char, _Traits = std::char_traits<char>, std::ios_base::openmode = std::_Ios_Openmode]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/fstream:702:7: note:   no known conversion for argument 1 from 'std::string {aka std::basic_string<char>}' to 'const char*'

更新2：我已经按照Paul Evans的建议完成了

string outFileName;
ifstream inFile;
ofstream outFile;
char inputFileName [fileNameSize+1];
cout << "How many files are being processed?\n";
cin >> fileCount;
cout << "What is the output file name?\n";
cin >> outFileName;
const string outName(outFileName);

和

outFile.open(outName);

现在我收到此错误消息：

closed4Ahrens.cpp: In function 'int main()':
closed4Ahrens.cpp:70:17: error: no matching function for call to 'std::basic_ofstream<char>::open()'
closed4Ahrens.cpp:70:17: note: candidate is:
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/fstream:702:7: note: void std::basic_ofstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char, _Traits = std::char_traits<char>, std::ios_base::openmode = std::_Ios_Openmode]
/opt/csw/lib/gcc/i386-pc-solaris2.10/4.6.3/../../../../include/c++/4.6.3/fstream:702:7: note:   candidate expects 2 arguments, 0 provided

Answer 1

在没有初始化的情况下告诉编译器outfile是const，请不要这样做。这样做：

 const string outName{"The path of the outfile"};

或

string outFileName;
// get outFileName
const string outName{outFileName};

创建文件并写入，文件名是用户输入？

1 个答案: