std::freopen
From cppreference.com
| Defined in header <cstdio>
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First, attempts to close the file associated with stream, ignoring any errors. Then, if filename is not null, attempts to open the file specified by filename using mode as if by fopen, and associates that file with the file stream pointed to by stream. If filename is a null pointer, then the function attempts to reopen the file that is already associated with stream (it is implementation defined which mode changes are allowed in this case)
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[edit] Parameters
| filename | - | file name to associate the file stream to | ||||||||||||||||||||||||||||||||||||||||
| mode | - | null-terminated character string determining new file access mode
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| stream | - | the file stream to modify | ||||||||||||||||||||||||||||||||||||||||
[edit] Return value
stream on success, NULL on failure
[edit] Notes
freopen is the only way to change the narrow/wide orientation of a stream once it has been established by an I/O operation or by std::fwide.
[edit] Example
The following code redirects stdout to a file
Run this code
#include <cstdio> int main() { std::printf("stdout is printed to console\n"); if(std::freopen("redir.txt", "w", stdout)) { std::printf("stdout is redirected to a file\n"); // this is written to redir.txt std::fclose(stdout); } }
Output:
stdout is printed to console
[edit] See also
| opens a file (function) | |
| closes a file (function) | |
| C documentation for freopen
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