fwide
来自cppreference.com
| 在标头 <wchar.h> 定义
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| int fwide( FILE *stream, int mode ); |
(C95 起) | |
若 mode > 0 ，则试图令 stream 为宽取向。若 mode < 0 ，则试图令 stream 为字节取向。若 mode==0 ，则只查询流的当前取向。
若已经决定流的取向（通过执行输出或通过之前调用 fwide ），则此函数不做任何事。
参数
| stream | - | 指向修改或查询的 C I/O 流的指针 |
| mode | - | 大于零的整数值设置流为宽，小于零的整数值设置流为窄，零为仅查询 |
返回值
若流在此调用后为宽取向，则为大于零的整数，若流在此调用后为字节取向，则为小于零的整数，若流无取向，则为零。
示例
下列代码设置并重置流的取向。
运行此代码
#include <wchar.h> #include <stdio.h> #include <stdlib.h> void show_orientation(int n) { n < 0 ? puts("\tnarrow orientation"): n > 0 ? puts("\twide orientation"): puts("\tno orientation"); } void try_read(FILE* fp) { int c = fgetc(fp); if(c == EOF) puts("\tnarrow character read failed"); else printf("\tnarrow character read '%c'\n", c); wint_t wc = fgetwc(fp); if(wc == WEOF) puts("\twide character read failed"); else printf("\twide character read '%lc'\n", wc); } int main(void) { enum fwide_orientation { narrow = -1, query, wide }; FILE* fp = fopen("main.cpp", "r"); if (!fp) { perror("fopen() failed"); return EXIT_FAILURE; } puts("1) A newly opened stream has no orientation."); show_orientation(fwide(fp, query)); puts("2) Establish byte orientation."); show_orientation(fwide(fp, narrow)); try_read(fp); puts("3) Only freopen() can reset stream orientation."); if (freopen("main.cpp", "r", fp) == NULL) { perror("freopen() failed"); return EXIT_FAILURE; } puts("4) A reopened stream has no orientation."); show_orientation(fwide(fp, query)); puts("5) Establish wide orientation."); show_orientation(fwide(fp, wide)); try_read(fp); fclose(fp); }
可能的输出：
1) A newly opened stream has no orientation. no orientation 2) Establish byte orientation. narrow orientation narrow character read '#' wide character read failed 3) Only freopen() can reset stream orientation. 4) A reopened stream has no orientation. no orientation 5) Establish wide orientation. wide orientation narrow character read failed wide character read '#'
引用
- C17 标准（ISO/IEC 9899:2018）：
- 7.29.3.5 The fwide function （第 309 页）
- C11 标准（ISO/IEC 9899:2011）：
- 7.29.3.5 The fwide function （第 423 页）
- C99 标准（ISO/IEC 9899:1999）：
- 7.24.3.5 The fwide function （第 369 页）
参阅
| (C11) |
打开文件 (函数) |