fflush

一、用到的函数 umask linux中的 umask 函数主要用于：在创建新文件或目录时 屏蔽掉新文件或目录不应有的访问允许权限。 文件的访问允许权限共有9种，分别是：r w x r w x r w x（它们分别代表：用户读 用户写 用户执行 组读 组写 组执行 其它读 其它写 其它执行） 其实这个函数的作用，就是设置允许当前进程创建文件或者目录最大可操作的权限，比如这里设置为0，它的意思就是0取反再创建文件时权限相与，也就是：(~0) & mode 等于八进制的值0777 & mode了，这样就是给后面的代码调用函数mkdir给出最大的权限，避免了创建目录或文件的权限不确定性 第一位代表了一项特别的安全特性，叫作粘着位（sticky bit），后面的3位表示文件或目录对应的umask八进制值。要理解umask是怎么工作的，得先理解八进制模式的安全性设置。 八进制模式的安全性设置先获取这3个rwx权限的值，然后将其转换成3位二进制值，用一个八进制值来表示。在这个二进制表示中，每个位置代表一个二进制位。因此，如果读权限是唯一置位的权限，权限值就是r--，转换成二进制值就是100，代表的八进制值是4。下表列出了可 能会遇到的组合。 原文链接： https://blog.csdn.net/qq_32767041/article/details/81191866 S_IFIFO|0666

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: What I'm trying to understand is whether LogonUser with LOGON32_LOGON_INTERACTIVE produces restricted token or not? Here is my code: int davai() { FILE * fp; fp = fopen ("C:\\tmp\\davai.txt", "a"); fprintf(fp, "shevedi davai"); fflush(fp); HANDLE token = NULL; HANDLE dupToken = NULL; if(!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY | TOKEN_DUPLICATE, &token)) { fprintf(fp, "davai: OpenProcessToken cheijva. %d\n", (int)GetLastError()); fflush(fp); } if (DuplicateTokenEx(token, MAXIMUM_ALLOWED, NULL, SecurityDelegation, TokenPrimary,

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Consider the following two macros: #define PNORM( v, s, ... ) { \ if( VERBOSITY_CHECK( v ) ) { \ if( ( errno = pthread_mutex_lock(&server.output_mutex) ) ) { \ PERROR_LOCKFREE( normal, "\tpthread_mutex_lock failed on output_mutex.\r\n" ) ; \ } \ fprintf( stdout, s, ## __VA_ARGS__ ) ; \ fflush( stdout ) ; \ if( ( errno = pthread_mutex_unlock(&server.output_mutex) ) ) { \ PERROR_LOCKFREE( normal, "\tpthread_mutex_unlock failed on output_mutex.\r\n" ) ; \ } \ } \ } #define PERROR_LOCKFREE( v, s, ... ) { \ if( VERBOSITY_CHECK( v ) ) { \ PERRNO ;

I am only allowed to use the standard c library so fpurge() is not an option form me. int dim = 0; int c = 0; printf("Please enter a number"); while ( (( c = scanf("%d",&dim)) != 1 ) || (dim < 1) || (dim > UCHAR_MAX) ) { if (c == EOF) { return 0; } fflush(stdin); printf("[ERR] Enter a number\n"); printf("Please enter a number"); } The program should read in a number big than one and if there is any “wrong” input like letters it should go and deliver an error message. It works with fflush on my windows pc put the program should run on a Linux system. How can I replace fflush that the programm

I'm sorry for this silly question. I have C program to prompt user to enter age and name and then print the age and name to the screen. This is my exercise that I read from book. This the program: #include <stdio.h> int main (void) { int age; char name[20]; puts("Enter your age:"); scanf("%d",&age); fflush(stdin); puts("Enter your name:"); scanf("%s",name); printf("Your age is %d\n",age); printf("Your name is %s\n",name); return 0; } When I enter extra characters to the first scanf() the program terminates and assign the extra characters to the next scanf() And then I changed the code, and add

I am writing a function where I only need to obtain a single digit, I decided to use getchar() instead of scanf(). However since I only need one character I did not use an array to obtain it. This causes a problem because I dont have a loop to find the '/n' character. To make sure my buffer is cleared before using getchar() again, I wrote this: while (getchar() != '\n'){} It works as I need it to, but is this the "correct" way to go about this problem? I tried using fflush(stdin), but it seems to not have any effect. Thank you for all replies, I check the comments often and would love to

Right when I am at fflush(stdout) and I break there in GDB, can I know what is there in stdout before I actually print it? How can I know what is there in stdout at any point in time? You almost certainly can, but you probably shouldn't. The standard requires only that FILE be a type that is useful to the implementation to identify an open file and whatever state is required to implement the semantics of the various functions that operate on streams. I'd generally agree with other posters that fflush() is a reliable way to know what you actually wrote to the file. However, if you have lost

I'm writing a large file > 7MB from an Oracle stored procedure and the requirements are to have no line termination characters (no carriage return/line feed) at the end of each record. I've written a stored procedure using UTL_FILE.PUT and I'm following each call to UTL_FILE.PUT with a UTL_FILE.FFLUSH. This procedure errors with a write error once I get to the point where I've written more than the buffer size (set to max 32767) although I'm making the FFLUSH calls. The procedure works fine if I replace the PUT calls with PUT_LINE calls. Is it not possible to write more than the buffer size