C :: Assign Strings To Double Pointer
May 2, 2013
When I try to assign strings to a double pointer, it only prints out the last string when I try to print everything out, and then it segfaults.
Code:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
main(){
char **test = calloc(3,sizeof(char));
[Code] .....
Am I assigning something the wrong way? Also, I am trying to avoid using array notation in order to practice, at least for the assigning of the strings.
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Jun 4, 2013
I am writing a math program, using variables of type double, and had initialized all variables to 0.0.
I now realize that not all results will be valid.
Is there a way to explicitly assign a variable of type double a non-numeric value, for example, "NaN", "Undefined", or "Unassigned" or something like that?
That way, when I read through the printout of results, I will realize the "NaN" results indicate a valid solution was not found. Whereas a 0.0 might not stand out.
I'd hate to have to go back and delete the initialization, and then re-assign 998 values just for the sake of 2 non-solutions.
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Mar 7, 2013
I have a function:
const void insertStuff(const void *key, const int value){
// I want to convert the void pointer into one
// of three types of pointers(int, string, or double)
switch(value){
case 0:
int *intPtr = key;
[Code] .....
But this causes an error of: "crosses initialization of int*intPtr"
What's the correct way of implementing this?
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Jan 24, 2013
How can we assign a pointer to a function? const char* function_name(), here what exactly does the pointer point to?
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Jan 15, 2015
Why would you ever assign a pointer to an existing array?Take this link for example. URL....I understand that pointers use dynamic memory allocation so they are much more flexible then a built in array, but if you already have an existing array, don't you already have static memory allocation for that array? Why bother assigning a pointer? Regardless of the pointer, doesn't the program still allocate static memory to the array anyway?
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Mar 22, 2014
I have this code:
Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
[code]....
What I want is basically to assign to the *p the pointer of the string so that i could do the following printf(" print string %s",*p); so i dont know how to do that.
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Aug 10, 2013
I can assign values to pointer character array like this...
Code:
char *array[4]={"abc","xyz","dgf","sdt"} ;
but the case is i don't know how to assign strings through key board ???? with using gets ,getchar or other suitable function
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Apr 22, 2013
I want to use getline to read stuff from a file that looks like:
Student ID:88152; Grades: 83.67, 92.45, 74.43, 97.95, 76.45; Name:Abercrombie, Neil
Student ID:92485; Grades: 77.65, 92.31, 60.47, 67.12, 99.64; Name:Aderholt, Robert
Student ID:10623; Grades: 37.95, 83.11, 64.46, 74.76, 95.30; Name:Alexander, Rodney
Student ID:76793; Grades: 53.13, 81.02, 83.71, 90.75, 88.92; Name:Baca, Joe
I have to print to the screen the id numbers, the grades and the names
I'm using getline but im having trouble print out the grades
It gets and displays everything except the grades. One of the grades only gets displayed
It should be a while loop, but im just working with the first line for now
ifstream inf;
char fileName[ MAX_STR_LEN ] = "ex.txt";
char testStr[ MAX_STR_LEN ];
int testInt;
double testDouble;
[Code] ....
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Aug 26, 2014
I am trying to convert multiple lines of strings to double with std::stod .... I used the code found on the website:
#include <iostream>
#include <sstream>
#include <string>
#include <fstream>
int main() {
std::string two_doubles =" 22145.365 -3564789";
std::string::size_type K;
double first = std::stod (two_doubles, &K);
double second = std::stod (two_doubles.substr(K));
}
The string starts with white spaces. I get this error message when compiling:
warning unused variable 'first'
warning unused variable 'second'
How do you convert the two numbers in the string two_doubles to doubles?
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Oct 24, 2013
I'm writing a program involving a theoretical hotel. Most of the code is already written, but the part I'm having trouble with involves the very beginning of the code.
The program is designed to read in from an input file the hotel's ID number, the types of rooms it has, the Room Numbers of each room, the base rate for each room, and the rate of additional charge per person.
The code demonstrates inheritance for my Object-Oriented Programming class, as each type of room will inherit from generic class Room, but I can't seem to figure out how to make the double-pointer for dynamic allocation work.
The code is below.
Hotel.h
Code:
class Hotel{
int hotelID;
static const int MAX_SIZE = 101;
Room **rPoint;
[Code] ....
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Apr 22, 2013
I have a double pointer, and I need to read words into it. Here's what I have so far:
Code:
while(fscanf(keywordFile,"%s",keyinputter)==1){
keys_cnt++;
}
keywords = (char**)calloc(keys_cnt,sizeof(char));
[Code]....
keyinputter is an array of size 30. The first while loop finds the number of words in a file so that I can calloc the correct amount of space for the double pointer, keywords. The second while loop is supposed to read the words into the double pointer, but when I run a print statement to print the string at keywords[0], it only prints null and not the word. Am I assigning the strings to the double pointer in the wrong way?
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Aug 1, 2013
How to initialize double pointer array..?
int (**aLines)[2];
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Feb 24, 2015
I have recently come across a function call that I do not understand. It uses the arrow operator for a function call, twice, and I don't understand.
Code:
static inline void b43_write32(struct b43_wldev *dev, u16 offset, u32 value)
{
dev->dev->write32(dev->dev, offset, value);
}
I see that the function itself does not return anything but calls another function. The main difficulty I have is with the "dev->dev->" operator, where dev, I expect is a pointer to a structure.
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Dec 22, 2014
I have int pointer called p and i want to calculate average.Since average involves using double or float so i am trying to convert this in the function averagetemp. It still gives me an error saying "cannot be converted"...
#include <iostream>
using namespace std;
int* createArray(int n);
int lowesttemp(int *p,int f);
int highesttemp(int *p,int f);
double averagetemp(int *k,double f);
void print(int *p,int lowest_temp,int highesttemp,int average_temp);
[Code] ....
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Mar 1, 2014
Why do most C examples pass a double pointer when manipulating linkedlists? Why can not we just pass a single pointer to the struct?I think using an external reference accessor for a linked list would be a more appropriate solution, yes or no?
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Nov 30, 2014
The following code compiles and runs fine till it reaches line 16 and gets a sigsev violation which I'm not sure about as to why. I have no problem passing the object of type node** into the constructor of base and storing it into the double pointer node** copy;; but when I call the function void pass(node** temp) it crashes.
#include <iostream>
class base;
class node {
private:
node** data;
public:
[Code] .....
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Jan 3, 2015
I am trying to make a pointer to pointers for strings with malloc but my code isn't right.I tried something like that.
Code:
char **p;
**p=malloc(100*sizeof(char*));
for(int j=0;j<100;j++)
*(p+j)=malloc(10*sizeof(char));
how could i allocate memory is only needed for every string(as long as it is)? Cause in my code i allocate memory for 100 strings and for 10 characters for every string.
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Mar 15, 2015
how to accommodate double-size:8 bytes in 4 bytes pointer in 32bit system.
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Apr 7, 2013
I am programming a translator, and I have it so that it detects words with spaces both in front of and behind them, so I did "string.append(space);" where space equals " ". That added a space to the end, but I still need a space added to the front.
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Feb 12, 2014
I have a problem who must print the sentences who have lenght more than 20 characters. I dont know why, but it prints just the first words. Look what i made.
#include<stdio.h>
#include<conio.h>
int main()
[Code]....
For instance :
Give the number of sentences : 3
First sentence : I like the website bytes.com
Second sentence : I like more the website bytes.com
Third sentence : bytes.com
After I compile the program it should print the first two sentences.
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Oct 2, 2014
This is my code , i should Assign value val to interval [keyBegin, keyEnd).
#include <assert.h>
#include <map>
#include <limits>
void assign( K const& keyBegin, K const& keyEnd, const V& val ) {
if(!(keyBegin<keyEnd))
[Code] .....
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Jun 18, 2013
I have array of pointers and when i tried to assign values dynamically all array items have the same value which is last value.
char* list[];
int DynamicDemo(void)
{
[Code].....
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Apr 21, 2013
I am having some difficulties knowing how to assign city to the list.
Code:
class DestinationList
{
private:
int num;
// number of objects in the list
Destination list[MAX_CITIES];
// array of destinations
public:
[Code]...
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May 26, 2013
Im starting with C. Like I said in the title, how do I assign the value from a function to a variable? I mean I have this function:
Code:
int EnteroAleatorio(){
rand();
return rand();
}
and I would like to assign the value of EnteroAleatorio to a variable in my main function, but when I try to do it and compile, I got the next error: non-lvalue in assignment
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Apr 24, 2015
I have a silverlight app that uses TextBox XAML controls.
In the c++ code-behind, IXRTextBoxPtr types are associated with these textboxes using "FindName" like this:
FindName(L"ColNum3", &m_pColNum3);
(where ColNum3 corresponds with the XAML CODE like this: )
Then, the code assigns the pointer like this:
std::wstring wsTransfer; // gets the wstring from imput
const WCHAR * wpszInput;
wpszInput = wsTransfer.c_str();
m_pColNum3->SetText(wpszInput);
but the display does not show the text data.
What am I missing? What steps am I missing to have this text modification display on the screen?
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Dec 3, 2012
Below assignation? It is a bit confusing.
myString = ""myInteger"is";
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