C/C++ :: Writing And Reading From Standard Input
Mar 18, 2015
I have an HTTP/1.0 webserver that I'm building in C that needs to exhibit CGI script functionality. Specifically, what I'm having trouble with is that I have two processes: process 1 is the webserver, process 2 is the CGI script. I fork in the webserver, and then call exec to run the CGI script (specifically, I used execv()). I've read from the CGI specifications in the RFC that in the case of a webserver receiving a POST request, the CGI script should read the arguments for the POST request from stdin. However, when I write to stdin, it simply echoes what was written to the terminal window and when the CGI script tries to read from stdin, it blocks.
So, with all that said, I'm pretty sure there is some simple conceptual explanation to my problem, but I can't figure it out. Do I need to use pipes or some form of interprocess communication to send the data from the webserver to the CGI script, or can it just be done with stdin (and possible stdout)?
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Apr 17, 2013
How to write a formula for standard deviation but im having a hard time ?
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Jul 12, 2014
I'm having some trouble working out how to read the console output in realtime, here's my code:
The button which starts the console application:
private void HELPRUN_Click(object sender, EventArgs e)
{
this.Output.Text = "";
[Code]....
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Mar 21, 2013
Here's my code, it's for a poker hand evaluator
input:
'ad 2d 3d 4d 5d...
...4s 5s 6s 7s 8s'
I think it should go through all the 10 crads and disply the name of each card, but it seems to only do it for the second hand
Code:
include <stdio.h>
#include <ctype.h>
int main( void ) {
char inputtedhand[64];
int z=0, counter=0;
int index;
int i=0,m=0,n=0;
[Code].....
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Oct 30, 2013
so i'm using scanf() this way
Code:
int i;
while (scanf("%i", &i))
printf("%i ", i);
printf("
done
");
i tried several combination of Ctrl+D and "Enter", it's not terminating, Ctrl+C just "cancels" the whole thing without printing "done", i'm running this on linux installed on a PC
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Mar 5, 2014
So I'm working on an assignment that is roughly about implementing the grep utility, only it has to be programmed in C. The weird nuance of the assignment is that while we are implementing the utility, we can use grep only we cannot pass grep a filename to search through(we are supposed to pipe a line from the file to standard input so that grep can examine it there.) Anyways, when I reach execlp, it will print out what is in stdin from the terminal, but it hangs at that point and I have to press Ctrl+Z to exit. I probably have the most difficulty with using this function, so I came up with a smaller scale model to get the basics down. Anyways, here's my code:
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(int argc, char* argv[]){
[Code] ....
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Dec 25, 2014
I'm trying to check to see if a string from standard input is alphanumeric or not. I feel as though there may be a function for this but...
Code:
for(test_pass = i; test_pass < i; i++){
if(test_pass[i] == ('1', '2', '3', '4', '5', '6', '7', '8', '9', '0'))
printf("Your password is alphanumeric!
");
}
The compiler wasn't too happy with this.
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Nov 1, 2013
So running the following code
Code:
#include <stdio.h>
int main(void) {
char c;
int i=1;
while (scanf("%c", &c)==1)
printf("loop sequence %i: %c(%i)
[Code] ......
Done it seems a "carriage return" serves two purposes here, one is to signal the program to read in the character typed in before the "carriage return", another serves as a second character typed, how can i do this cleanly, that is without having to use a "carriage return" as the second character to signal "I've typed in the first character already".
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Dec 24, 2014
I've been experimenting a bit and can't find a decent way to make a brute forcing script that accepts a password from standard input, and goes through all possible combinations until it is matched. How to structure the code?
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Feb 19, 2014
Write code to do the following:
1) declare a variable ptr as a pointer to int and initialize it to NULL
2) dynamically allocate memory for an array of 100 elements
3) read 100 elements from the standard input device and store them in the array.
This is what I have so far, I'd like to know if its ok or if something is wrong.
int *ptr = NULL;
ptr = new int[100];
cin >> dataPtr [arr];
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Apr 13, 2014
A Bookseller makes special discount for multiple orders of a book as follows:
AMOUNT and DISCOUNT as follows.
5-9 5% 10-14 10% 15-19 15% 20+ 20%
Write a C main function to read the amount of order from the standard input and compute and print the total price of the given order after the discount. Assume that unit price of a book is 10.00$
My problem is that.When i start with this
Code:
#include<stdio.h>
#include <stdlib.h>
int main(void)
{
int number;
float TotalPrice;
printf("enter a number:");
[Code] ....
I get 0 if i enter a number between 0 and 4(0 and 4 included). I don't know where I am doing a mistake. I also want to know if i can handle this buy just if statements. or how can i do it by while and for loops ?
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Nov 3, 2014
I'm writing a program using Huffman algorithm to compress text file. I have tested my program by just printing the printing ASCII character to file and it worked fine. However, now I have to implement using bits and my program doesn't work. It seems like I'm not reading or writing the right bits. Here is the result of my testing:In the input file I put abc the input file to compress it. Then I uncompress it the out out is aaa. Below is a snippet of how I read and write bits
Code:
class BitInput {
istream& in; // the istream to delegate to
char buf; // the buffer of bits
int nbits; public:
BitInputStream(istream& s) : in(s), buf(0), bufi(8) { }
[Code] ....
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Sep 19, 2013
I have a text file containing 500 signed decimal numbers. My task is to read each entry and convert into a 16-bit 2's complement representation (binary number) and write into the another text file.
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Mar 19, 2013
Code:
#include <stdio.h>
struct hardware{
int recNum;
char toolName[30];
int quant;
double cost;
[Code] .....
I'm having issues with my functions working properly. I'm not sure where I'm going wrong with them and if i'm using the correct mode for the fopen.
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Feb 20, 2015
I have to write a program that sorts names and grades from a file and output them to another.
For example:
Name: Peter Parker
Exam 1: 95
Exam 2: 90.625
Exam 3: 91.20
Name: Mary Smith
Exam 1: 65
Exam 2: 79.1234
Exam 3: 70.24
Becomes something like this in the output file:
Name: Parker, Peter
Average Score: 92.28
Grade: A
Name: Smith, Mary
Average Score: 71.45
Grade: C
I know I'm supposed to read the whole file, but I'm getting really confused on how to take the name of each student separately without recording Exam 1, 2, and 3. I'll be able to do the average score and grade on my own.
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Apr 30, 2013
Is there a way to read and write to the same file?
I'm writing a game program and I want to save the score at the end of the game to a txt file. The txt file already contains other game scores. How do I store the score without overwriting the previous scores.
I'm just using basic fstream.
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Oct 28, 2013
I have to make a program that asks for your username (any)to register it. When you type it it will say something. I want to create a txt file also. so this is what I have:
#include <iostream>
#include <fstream>
using namespace std;
int main() {
int a;
{
ofstream myfile;
[Code] ....
now, how can I use the cout again to print something "Welcome to the program..."?
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Nov 3, 2014
I'm writing a program using Huffman algorithm to compress text file. I have tested my program by just printing the printing ASCII character to file and it worked fine. However, now I have to implement using bits and my program doesn't work. It seems like I'm not reading or writing the right bits. Here is the result of my testing:In the input file I put abc the input file to compress it. Then I uncompress it the out out is aaa. Below is a snippet of how I read and write bits
public:
BitInputStream(istream& s) : in(s), buf(0), bufi(8) { }
/** Read the next bit from the bit buffer.
* Return the bit read as the least significant bit of an int.
*/
int readBit(){
int i;
if(nbits == 8){
buf = in.get();
[Code] .....
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Jan 16, 2015
I'm messing around with reading and writing files. The first file creates a small txt file. Simple enough
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main(){
string name;
string desc;
[Code] ....
It does what it should. It creates a text file "items.txt" .... It reads as such:
dagger,a dagger,15,10,0,1,3,1,0,0,0,1,0,0,0,0,0,1
The second file is meant to read the file and place the data back into the variables. This happens, but the data crams itself into the first variable, and the rest of them collect the trash that's in memory.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
string name,desc;
[Code ....
I need to get "dagger" into name, "a dagger" into description, and each value with their perspective variable. I'm sure I need some type of "separator". Hopefully I can use the comma. Before it's over, I will have about a hundred items that will need to be read into a class of items.
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Dec 10, 2013
program that I am working on. I want to use fgets() in my program so I could handle multiple words from a text(to be able to handle spaces). I get a weird result when running the program.
Code: #include <stdio.h>
#include <stdlib.h>
//#include "kim.h"
#include <string.h>
[code]....
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Oct 16, 2013
I have a file of data where each line consists of 4 parameters (degree, alpha, beta and x) and a value corresponding to these, organized in increasing order of the parameters. Here's the test file I'm using:
0 1 1 0.5 3.5
1 1 1 -0.5 -0.5
1 2 0 0.2 4.5
1 3 0 0.2 -4.5
2 0 0 1.5 2.1
2 1 0 0 5.6
My code is supposed to look for a certain set of parameters (currently set to 1 2 1 1.5, which is not contained in the file) and its value. If it's there (i.e. the file contains the value for the right parameters) the program is done. If not it should calculate the value using a function JacobiPoly() and insert the wanted parameters and corresponding value in the appropriate place in the file.
I have a code in which I think everything works except the writing to file. I use an fstream so I can both read and write and open it with ios::out||ios::in. I'm also aware I need something similar to fseek in between input and output but according to [URL] .... reading and writing to the same file using the same fstream, seekp() should suffice. I'm using seekp(), but the output (in the form inout << (...)) doesn't work.
Here's the code:
fstream inout;
inout.open("inouttest.dat", ios::out | ios::in);
int degree=1, readDeg;
double alpha=2, beta=1, x=1.5, value, readAlpha, readBeta, readX, readVal;
bool foundVal=false;
streampos beforeRead=(streampos)0;
[Code] ....
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May 19, 2014
How to write the code for this with the following requirements:
download the text file weblog.txt
This file is an Apache web log taken from the web server for St. Mary's University. When a visitor goes to their web site, the visitor's browser makes a request to the web server to view a web page, which is a file residing on the server. Each time a page is requested by a browser, the web server records information about that request. This weblog.txt holds the details of some of those requests.
Create a non-member function to read each line of the web log file. This function must do error checking to ensure that the file is opened successfully, otherwise it must provide a message like "file not available" to the user.
Each line should then be stored in a vector such that the first element of the vector is the first line of the web log file. Because each element will hold an entire line from the file, the vector should be declared as a vector of strings.
Note: You must declare the vector in a function.
Create another non-member function to sort the contents of the vector. Make sure to pass the vector by reference or your sort will disappear when the function ends! Use the sort function with #include <algorithm> to do the sort; you do not have to write your own sort algorithm.
Create one more non-member function to write the contents of the vector to a file. Each element should be on its own line in the new file. The contents of the new file should look like the original input file once your program completes, but in sorted order.
Create a main function that calls all of your non-member functions.
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Jan 19, 2015
I am trying to make a project using arduino to control several power surces by time, i don't want to have an lcd, that would be easyer but i don't have enought space on my project, i want to set the time and the timing for the relays via Serial
Of curse i could set it using the serial monitor on the arduino ide, but i want to make a simple program to make the pc comunicate with the arduino and make it simpler to set the time and similar stuff. How to use one of my usb ports to print and read serial data?
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Dec 7, 2014
I am attempting to read a ppm file. When i do it i try to write it back in another file just to see how's done and i get a terrible result. I assume the problem is something with the casting i do to the variables.
This is my image class
Image:: Image(unsigned int width, unsigned int height, bool interleaved) {
buffer = new Component [3*width*height];
this->height=height;
this->width=width;
this->buffer=Component();
[Code] .....
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Jun 5, 2014
why I'm giving "Access violation reading location 0x336827B8" and also I was able to read my data but it's giving me weird stuff. I want to write the sorted grades and the average in a new disk file. so here's my code so far here's my code
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
int avg(int sum, int size);
void swap(int *, int *);
[code]....
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Mar 6, 2013
I am having problems either writing data to a binary file or reading from the file. Through the process of elimination I am posting the code where the data is written to file to see if I can eliminate that as an option. I know the data is being processed correctly because, through the use of another function, I can view the data.
I also know that fwrite must be including some padding because the file size ends up being 576 bytes after it is written instead of 540 bytes (the size it would be if no padding is used). Here is my struct:
Code:
typedef struct {
char teams[25];
float wins;
float losses;
float pct;
int runsScored;
int runsAgainst;
} STATISTICS;
Here is where I initialize it:
Code:
STATISTICS stats[12] = {
{"Anaheim Arrays", 0.0, 0.0, .000, 0, 0},
{"Pittsburg Pointers", 0.0, 0.0, .000, 0, 0},
{"Indianapolis Integers", 0.0, 0.0, .000, 0, 0},
[Code] ....
And here is the function that writes my data. The sA array is only used to change the scheduled games based on the variable week.
Code:
void schedule(STATISTICS stats[]) {
FILE *f;
int sA[12], week = 0, runsPerGameA = 0, runsPerGameB = 0, runsAgainstA = 0, runsAgainstB = 0;
int index, a = 0, b = 1, i = 0;
[Code] .....
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