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Defined in header <cwchar> | ||
int fwide(std::FILE* stream,int mode); | ||
Ifmode>0, attempts to makestream wide-oriented. Ifmode<0, attempts to makestream byte-oriented. Ifmode==0, only queries the current orientation of the stream.
If the orientation of the stream has already been decided (by executing output or by an earlier call to fwide), this function does nothing.
Contents |
| stream | - | pointer to the C I/O stream to modify or query |
| mode | - | integer value greater than zero to set the stream wide, less than zero to set the stream narrow, or zero to query only |
An integer greater than zero if the stream is wide-oriented after this call, less than zero if the stream is byte-oriented after this call, and zero if the stream has no orientation.
The following code sets and resets the stream orientation.
#include <cstdio>#include <cstdlib>#include <cwchar>#include <iostream> void show_orientation(int n){ n<0?std::wcout<<"\tnarrow orientation\n": n>0?std::wcout<<"\twide orientation\n":std::wcout<<"\tno orientation\n";} void try_read(FILE* fp){if(constint c=std::fgetc(fp); c==EOF)std::wcout<<"\tnarrow character read failed\n";elsestd::wcout<<"\tnarrow character read '"<<static_cast<char>(c)<<"'\n"; if(const wint_t wc=std::fgetwc(fp); wc== WEOF)std::wcout<<"\twide character read failed\n";elsestd::wcout<<"\twide character read '"<<static_cast<wchar_t>(wc)<<"'\n";} int main(){enum fwide_orientation:int{ narrow=-1, query, wide}; FILE* fp=std::fopen("main.cpp","r");if(!fp){std::wcerr<<"fopen() failed\n";returnEXIT_FAILURE;} std::wcout<<"1) A newly opened stream has no orientation.\n"; show_orientation(std::fwide(fp, fwide_orientation::query)); std::wcout<<"2) Establish byte orientation.\n"; show_orientation(std::fwide(fp, fwide_orientation::narrow)); try_read(fp); std::wcout<<"3) Only freopen() can reset stream orientation.\n";if(std::freopen("main.cpp","r", fp)==NULL){std::wcerr<<"freopen() failed\n";returnEXIT_FAILURE;} std::wcout<<"4) A reopened stream has no orientation.\n"; show_orientation(std::fwide(fp, fwide_orientation::query)); std::wcout<<"5) Establish wide orientation.\n"; show_orientation(std::fwide(fp, fwide_orientation::wide)); try_read(fp); std::fclose(fp);}
Possible output:
1) A newly opened stream has no orientation. no orientation2) Establish byte orientation. narrow orientation narrow character read '#' wide character read failed3) Only freopen() can reset stream orientation.4) A reopened stream has no orientation. no orientation5) Establish wide orientation. wide orientation narrow character read failed wide character read '#'
| opens a file (function)[edit] | |
C documentation forfwide | |
