fflush | 易学教程

windows console program stdout is buffered when using pipe redirection

阅读更多关于 windows console program stdout is buffered when using pipe redirection

问题 i have a long run server program(say, program A) which is written in QT/c++. the program is not so stable so i decide to write a python script to restart it if it crashes. the problem is that the program may started fail(if i gave it an in-use port), print the error and then just hang there without quitting, so i must monitor the stdout of the program and kill it on failed startup. this is a piece of my final code (well, in fact this is ok, you can just ignore it): self.subp = subprocess

How come fflush(stdin) function is not working?

阅读更多关于 How come fflush(stdin) function is not working?

问题 My main question is why is it that the fflush(stdin); function not working? Whenever I run the the code, I am not able to get the second input with space ex. Hello World but instead I get Hello?? thanks #include <stdio.h> main(){ int x; double y; char string[100]; /* * string input */ printf("Enter one word: "); scanf("%s", string); // note there is no & before string */ printf("The word you entered was >>%s<<\n"); printf("Enter many words: "); fflush(stdin); // <---- for some reason this

c - need an alternative for fflush

阅读更多关于 c - need an alternative for fflush

问题 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

Oracle PL/SQL UTL_FILE.PUT buffering

阅读更多关于 Oracle PL/SQL UTL_FILE.PUT buffering

问题 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

Is this the proper way to flush the C input stream?

阅读更多关于 Is this the proper way to flush the C input stream?

问题 Well I been doing a lot of searching on google and on here about how to flush the input stream properly. All I hear is mixed arguments about how fflush() is undefined for the input stream, and some say just do it that way, and others just say don't do it, I haven't had much luck on finding a clear efficient/proper way of doing so, that the majority of people agree on.. I am quite new at programming so I don't know all the syntax/tricks of the language yet, so my question which way is the most

C: Clearing STDIN

阅读更多关于 C: Clearing STDIN

问题 basically in codeblocks for windows before each printf I have "fflush(stdin);" which works. When I copied my code to Linux, it doesn't work, nor does any of the alternatives for "fflush(stdin);" that I've found. No matter which way I seem to do it, the input doesn't seem to be clearing in the buffer or something in my code is incorrect. #include <stdio.h> #include <math.h> #include <limits.h> #include <ctype.h> int main() { char pbuffer[10], qbuffer[10], kbuffer[10]; int p=0, q=0, k=0; int r,

Why isn't scanf( ) waiting for input from keyboard?

阅读更多关于 Why isn't scanf( ) waiting for input from keyboard?

问题 I have below C code. #include<stdio.h> int main() { //Declaring structure book. struct book { char name; float price; int pages; }; struct book b[5]; int i; //Below loop takes the info if 5 books from user for (i=0; i<5; i++) { printf("Enter name, price, and pages: "); fflush( stdin ); scanf("%c%f%d",&b[i].name,&b[i].price,&b[i].pages); } return 0; } However when I compile and run, something strange happens. -bash-4.1$ ./a.out Enter name, price, and pages: A 23 34 Enter name, price, and pages

using fflush on C++

阅读更多关于 using fflush on C++

问题 Can someone help me using fflush in C++ Here is a sample code in C #include <stdio.h> using namespace std; int a,b,i; char result[20]; int main() { scanf("%d %d\n", &a, &b); for (i=1; i<=10; i++) { printf("5\n"); fflush(stdout); gets(result); if (strcmp(result, "congratulation") == 0) break; } return 0; } This is program for getting interactive input. I usually use cin and cout so is it possible not using printf and scanf ? 回答1: The translation to C++ programming style is this: #include

printf函数与缓冲区

阅读更多关于 printf函数与缓冲区

printf函数与缓冲区 pr intf函数是一个行缓冲函数，先将内容写到缓冲区，满足一定条件后，才会将内容写入对应的文件或流中。基本条件如下： 1.缓冲区填满 2.写入的字符中有‘\n’ '\r' 3.调用fflush或stdout手动刷新缓冲区 4.调用scanf等要从缓冲区中读取数据时，也会将缓冲区内的数据刷新5.程序结束时有以下示例1验证： 1 #include <stdio.h> 2 #include <stdlib.h> 3 4 /*argc:命令行输入参数个数，argv:命令行参数 5 *argv为字符指针数组，argv[i]为指向第ｉ个命令行参数内容的指针 6 */ 7 int main(int argc, char **argv){　 8 int i; 9 char a='a'; 10 if(argc != 2) //命令行参数为２，否则出错 11 { 12 printf("Usage:%s Number\n",argv[0]);　 13 return 0; 14 } 15 16 for(i=0;i<atoi(argv[1]);i++) //atoi:字符转化为整数 17 { 18 printf("%c",a); 19 } 20 21 while(1); //让程序一直运行 22 } 运行结果：说明linux下，printf缓冲区大小为1024字节

C: Stdin - Removing Excess Data

阅读更多关于 C: Stdin - Removing Excess Data

问题 Short version I want to get rid of excess user input from stdin but I understand fflush(stdin) is not recommended. I found this replacement: int ch; while ((ch = getchar()) != '\n' && ch != EOF); However, if there is no excess data to remove, this will remove the user's next input. How can I check if there is data to remove from stdin so I can choose whether or not to use this method of clearing the buffer? Long version with explanation I'm making a command-line tool in Obj-C/C. I understand