C++ :: Unexpected Output From Fprintf?
Feb 11, 2014
I have the following piece of code which should write the contents of my vetor to y file but I am getting a very weird output in my file.
for (int i=0;i<amount;i++) {
fprintf(pFileO,"Case #%d: ",i+1);
for (int j=0;j<words[i].size();j++) {
[Code].....
As you can see this doesn't make sene because the file should also contain the exact same things as the cmd outputs. What's going on here ?
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Jan 21, 2015
I am currently trying to understand why this example for using an array as an argument in a function has a different result than what the lecture notes say it should be.
So supposedly sum should return with the value 28, but I get 27 no matter what. I also am not very good at reading and understanding what exactly the order of operations for this function are.
Code:
#include <iostream>
using namespace std;
int sum(const int array[], const int length) {
long sum = 0;
for (int i = 0; i < length; sum += array[++i]);
return sum;
[Code] ....
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Sep 14, 2013
I tried running the code below and i got an unexpected output
Code:
#include<stdio.h>
void main() {
char a='A';
while(a)
[Code] ....
The code is supossed to give an infinite loop but instead it terminates with a=0...I tried running it with some casting like this
Code:
#include<stdio.h>
void main(){
char a='A';
while((int)a)
[Code] ....
But the output was the same as before.why the code has this unexpected behaviour???
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Nov 8, 2013
So the latest challenge from jumping into c++ is as following.
Code:
Write a function that builds the multiplication table of arbitrary dimensions This chapter also talks a ton about 2d arrays.
So I've built my program thus far as this.
Code:
#include <iostream>
using namespace std;
int drawTable(int,int);
int main()
[Code] .....
So basically, the idea is that I can use the arrays dimensions as a placeholder, and just multiple them to get that specific spot, so table[0][0] = 0, [0][1] = 0 and so on. However the output actually seems to be randomly generated numbers so I'd like to ask, what am I doing wrong? Am I on the right track? Or have I missed the bus stop completely.
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Feb 28, 2014
i have two variables which are arrays and want them to be written below the other once all the values of one variable is written . how can i do that using fprintf function in c++ ?
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Aug 13, 2014
Its my 1st time using fopen,fprintf and others and i cant seem to edit my file via fprintf! Heres my program:
Code:
#include <stdio.h>
#include <stdlib.h>
char letter,check,nought,bleh,hi,a;
int main()
[Code]....
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Jan 3, 2014
Code:
struct sth {
char* str;
} pt;
}
[code]...
fprintf does not save string to file. How can I put structure into list?
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May 20, 2013
I have this error - [Error] 'fprintf' was not declared in this scope (line 32)
and this - [Error] 'fclose' was not declared in this scope (line 33)
here's my code.........
1 #include <iostream>
2 using namespace std;
3 #include <windows.h>
4 #include <winuser.h>
5
6 int save (int key_stroke, char *file);
[Code] ......
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Jan 11, 2015
I am trying to take text from a file and have it displayed using fprintf at line 46. When I run the below code nothing prints out. My text file has 4 lines with 5 different strings separated by whitespace.
#include <cstdlib>
#include <vector>
#include <cstring>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
using namespace std;
//declare my own struct
[Code]...
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Nov 5, 2014
I'm new to C and was wondering if it was possible to print multiple characters to the same file using the fprintf function provided in one of the C standard libraries?
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Jun 24, 2013
I am working through Binary IO with objects and am running into a curious error.
The program executes perfectly until it hits the very end. At "return 0", the program fails. The debugger picks up SIGABRT when executing "return 0". This seems to me to indicate a deconstructor problem of some kind. However, I can't seem to find any deconstructor problems (I am fairly new at programming though).
If I comment out the following two lines:
"binaryio.read(reinterpret_cast<char *>(&studentNew1), sizeof(Student));"
"binaryio.read(reinterpret_cast<char *>(&studentNew2), sizeof(Student));"
then the program finishes exiting without error . . . . but the whole point is to be able to read from the binary file. With those two lines in the code, the program successfully reads from the file and outputs the objects to the console ,but fails at "return 0";
Here is the code:
#include <iostream>
#include <fstream>
#include "Student.h"
using namespace std;
void displayStudent(Student student) {
cout << student.getFirstName() << " ";
[Code] .....
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Aug 7, 2013
I'm getting unexpected output in 2 different cases. The 1st deals with bitfields. The C++ standard has this line about integral promotions:
An rvalue for an integral bit-field (9.6) can be converted to an rvalue of type int if int can represent all the values of the
bit-field; otherwise, it can be converted to unsigned int if unsigned int can represent all the values of the bit-field.
If the bit-field is larger yet, no integral promotion applies to it. If the bit-field has an enumerated type, it is treated as any other value of that type for promotion purposes.
This sounds like the value of a bitfield will always be treated as a signed int if the signed representation of the value will fit in the bits. This seems to hold true for my C compiler, but not my C++ compiler.
I tried storing a small negative value in a bitfield that has enough bits to store the sign bit and the value. But when I print out the bitfield, I always get a large number
In the example code below, I expect the output:
Code:
foo.x = -1
foo.y = -2
foo2.x = 31
foo2.y = 6
foo3.x = -1
foo4.x = 4294967295 But I get: Code: foo.x = 31
foo.y = 6
foo2.x = 31
foo2.y = 6
foo3.x = -1
foo4.x = -1 -------------------
The other issue I'm having is sort of similar. I'm trying to store 4294967295 into a float, but when I print it out, I get 4294967296. i've tried storing a few other large values like this and what's printed out is rarely the value I stored. I thought it might be because of some int to float conversion, so I tried 4294967295.0. Still no luck. Then I remember that defaults to a double so maybe that's the issue so I tried 4294967295.0f. Still no luck. Why can't I store the correct value here? I don't think it's an IEE format thing since I can use these values as floats on a calculator program.
The example code showing both issues is below.
Code:
#include <stdio.h>
typedef struct {
signed char x : 5;
signed char y : 3;
}my_struct_t;
[Code] .....
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Jul 30, 2013
My compiler (GCC) keeps expecting an expression where it shouldn't in 1 specific piece of my code:
int zxcNewWindow( HWND parent, TCHAR *text, zxWINDOW *kid,
UINT style, int x, int y, int w, int h, int type )
// right here
{
*kid = zxDefWINDOW;
The project contains only 2 files right now and the settings are just the default for an empty Code::Blocks 12.11 project. Both files are in UTF-8 format (tried in ASCII too), I just cannot see why this is not compiling correctly. I'll post the files in the next two posts.
Edit: For those of you who didn't get what the error was from the above here's the full log:
mingw32-gcc.exe -Wall -g -DzxDEBUG -c C:MePrjscppzxGUImain.c -o objmain.o
C:MePrjscppzxGUImain.c: In function 'zxcNewWindow':
C:MePrjscppzxGUImain.c:39:10: error: expected expression before '{' token
Process terminated with status 1 (0 minutes, 0 seconds)
1 errors, 0 warnings (0 minutes, 0 seconds)
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Jun 20, 2013
i use dev c++...i write this code to reverse an array and save the result in the same one
if n=3 i expect
a[0]=0 a[1]=1 a[2]=2 (before rev is OK but after calling rev)
a[0]=2 a[1]=1 a[2]=0 (expected result )
but i get
n=3
[code].....
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May 2, 2013
I'm just starting c++, doing tutorials. So many tutorials. I've noticed that the tutorials all assume the same thing: That the user will always do exactly as he/she is told when asked for input.
Example: "Please enter your age:"
Now, the example code might be expecting the user to type some numbers, but what if the user feels like typing out the letters of their age?
"I am ninety five thank you very much, sonny"
I could specify to the user that I only want the information in number form, but what if the user is just being a dick?
What if the user types, "none o' yer business."?
So... how to approach "fool-proofing" player input?
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Oct 28, 2014
I have written this regex to match a floating point literal:
(^[[:space:]]*)(([0-9]+.?[0-9]*([eE][+-]?[0-9]+)?)|"
"(.[0-9]+([eE][+-]?[0-9]+)?))([fFdD]?[[:space:]]*)$
and when I match it with string like "123e" or "e2" it works while it shouldn't and I can't find the reason why.
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Oct 9, 2013
I keep getting a segmentation error when ever I have the following code...
int main(void) {
//Section 1
unsigned long val = 12;
std::vector<unsigned long> vval;
for(unsigned long i = 0; i < 100; ++i) {
vval.push_back((unsigned long)0);
[Code] ....
Error: *** Error in `/home/alex/projects/bignum/build/bignum': free(): invalid pointer: 0x00007ffff75b5b88 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x80a46)[0x7ffff7274a46]
compiler is clang++ 3.2
It doesn't happen if I restructure it so that bignum::num is not a pointer to an std::vector<unsigned long>
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Apr 1, 2014
I have a WordRecord that contains a LinkedList (both my doing). I have rigorously tested my LinkedList class, and know that it works (heck, I used it in the last project I had!). The problem is that undefined behaviour seems to happen when using the WordRecord, which has a std::string and a LinkedList<unsigned>. (The problem happens with the LinkedList.)
Here is the code:
main.cpp
#include <iostream>
#include "BinaryTreeNode.h" // here for test purposes
#include "LexicographicTree.h"
#include "LinkedList.h"//also for test purposes
#include "OutputStream.h"
#include "WordRecord.h"
using namespace std;
int main()
{
// setup the OutputStream to print to "test.txt"
OutputStream stream("test.txt");
// create a sampleWordRecord (make it have the word "I" on line 1)
[code]....
One of the requirements for the project is that it must compile on Unix server (I am using Windows, and have tested it in both environments.) I get a core-dump in the Unix environment. On the other hand, the output on-screen in the Windows environment looks right. However, when I open up the text file, I get the following
Sample word record:
WordLines
I{14}
/* I have no what is happening to sampleWordRecord's LinkedList; I am not trying to modify it, except for where I created the sampleWordRecord! */
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May 9, 2015
node = pool.at(0) is executed even though pool is empty,
I even tried pool.size() == 0, that line is still executed. What is the reason, I wonder?
Code:
NodePoolNode* NodePool::acquireNode(int x, int y, long t) {
std::stringstream key;
key << x << ":" << y << ":" << t;
NodePoolNode* node = usedNodes[key.str().c_str()];
if (node == NULL) {
[Code] ....
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Aug 23, 2013
I found this piece code on the following site:
[URL]
I predicted the outcome as being 01230 as I thought the prefix decrement operator on iterator ce would prevent the final element of the list from being transformed.
I was wrong, the correct output is 01234.
So, I removed the decrement prefix and ran the test again, expecting a different result. It wasn't! The result was still 01234.
Only when I decremented ce twice did I get the result I initially expected, 01230.
why the first decrement of ce appears to have no effect?
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <list>
#include <cstdio>
int main() {
typedef std::list<int> L;
[code]....
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Apr 30, 2014
I wrote a sequential matrix multiplication program in c.
After execution i get error like
./mul.c: line 11: syntax error near unexpected token `('
./mul.c: line 11: `int main(){'
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define wA (30 * 16)
#define wB (50 * 16)
#define hA (80 * 16)
#define hB wA
#define wC wB
[Code] ....
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Nov 11, 2014
My Windows service may download a binary update in the background using WinHTTP APIs. I'm using code similar to the one from the bottom of this MSDN page. For ease of access I'll copy if below:
Code:
DWORD dwSize = 0;
DWORD dwDownloaded = 0;
LPSTR pszOutBuffer;
BOOL bResults = FALSE;
HINTERNET hSession = NULL,
hConnect = NULL,
hRequest = NULL;
[Code] ....
The issue I'm experiencing is that while downloading, the code above "hogs" most of the bandwidth available on the client computer. My goal is to make it "throttle" itself on a configurable "bps" level, say at 50 kbps and not use any more bandwidth.
Someone suggested measuring my current download speed (in bps) and depending on the value make the thread "sleep" before calling WinHttpReadData again.
So the formula I'd use to calculate BPS is this:
BPS = (BytesDownloaded * 1000 * 8) / TimePassedInMilliseconds;
Then to convert to Mbps:
Mbps = BPS / (1024 * 1024);
And the waiting/sleep would be done as such:
Code:
DWORD DesiredBitsPerSec = 50 * 1000;//for 50 kbps
if(fBps > DesiredBitsPerSec) {
DWORD dwW = (DWORD)((fBps - DesiredBitsPerSec) * 1000) / DesiredBitsPerSec;
if(dwW > 0)
::Sleep(dwW);//Sleep to throttle the download speed to the one we need
}
So I implemented it into the code above but it didn't work -- the Sleep API would produce very strange delays. So I decided to add a little bit more tracking code to actually be able to see what BPS values I'm getting.
I created a small test project that is attached to this post to illustrate the issue. (It's hard to explain without running an example.)
For a test I began downloading a large binary file (Windows 10 MSI, off Microsoft's server) and at the same time had the Task Manager open on a Performance tab that was showing me the current network throughput. I made a screenshot:
But as you can see, the reading on the test program and the actual network BPS values differ greatly.
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Dec 8, 2013
how to get the output of this program.. I'm not completely lost but I need it in the simplest terms.
Code:
/*Recursive Trace
Written by Ron
April 2006
*/
[Code]....
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Jul 21, 2013
is it possible to output like this using only one loop? if yes, how?
target output Code: ABCDE
EDCBA here is my code but using one loop im not getting my target output Code: #include <stdio.h>
main()
{
int x, y;
for(x='a', y='e'; x<='e'; x++, y--)
{
printf("%c
%c", x, y);
}
getch();
}
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Sep 21, 2014
So I have an array portfolio [i][j] where i and j are determined by inputs by the user. I can get the code to fill the array with the correct values; however, I can not figure out how to output the array to csv.
Is there a simple way to output to a csv? Is it easier to create the csv file and just write to it?
This is all I have so far:
for( i=0; i<sizevol; i++){
for(j=0; j<sizespot; j++){
myfile.open ('')
}
}
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Mar 17, 2013
In my code the cout phrase is supposed to give me an angle in degrees. no matter which 2 points i enter in, it always outputs the angle between them to be 57. This is because the acos value of 0 in degrees is 57. The program compiles without error.
Here is the code:
/*
Synopsis: This program reads in the coordinates of two 2D vectors and outputs the angle between the vectors in degrees.
*/
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
// function prototypes
// ENTER FUNCTION PROTOTYPE FOR normalize() HERE.
void normalize(double & x, double & y);
[Code] .....
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