C :: Dynamic Array Of Pointers To String
Jun 11, 2013
I have a little problem with one of my functions. The function purpose is to get a number (n) and create an array (size n) with pointers to strings (each string length is 20 chars) and i don't know why but during the debugging i get a <bad ptr> message and this message :
CXX0030: Error: expression cannot be evaluated
This is my function:
Code:
char** getlist(int n) {
int i=0;
char **arr;
arr=(char**)malloc(sizeof(char)*n);
if (arr==NULL)
[Code] ....
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Mar 12, 2014
The snippet below (or similar) compiles and runs OK but I am using Visual Studio C++ compiler. Are the lines where .nameFirst and .nameLast assigned kosher in ANSI C?
Also I am concerned about the memory allocation for these string constants. Does the runtime system put them on the heap? It doesn't seem that they are really constants since they are not defined before runtime.
Code:
#include "stdlib.h"
typedef struct
{
unsigned id;
char* nameFirst;
char* nameLast;
} myList;
[Code]...
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Jan 30, 2013
I am attempting to declare an array of pointers dynamically based on user input. I am not sure if A) I'm implementing the syntax of declaring a dynamic array correcntly and B) if my code is set up correctly to print otherwise.
int array_size;
cout << "Please enter the size of the array: " << endl;
cin >> array_size;
if(array_size >= 8) {
cout << "Invalid array size, please enter a valid integer size";
cin >> array_size;
[Code] .....
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Sep 23, 2014
I know that the synatx for a dynamic array of values is, for example:
int* a = new int[size];
And i understand that "a" is a pointer to the 1st element of the array on the heap.
Now, the syntax for a dynamic array of pointers is:
int** b = new int*[size];
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May 23, 2013
Suppose I wished to reallocate memory (resize) an array of pointers. Why does the following not work?(The program runs, yet yields a faulty segmentation error message. Why?):
Code: char **ptrarr = (char**) malloc(sizeof(char*))
Code: ptrarr = (char**) realloc(ptrarr, (capacity) * sizeof(char*));
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Jul 27, 2013
I coded a program that takes some strings and lexicographically orders the strings and its substrings. I have used dynamic memory allocation technique and its working fine for all strings without consecutive same alphabets.I use a list in which a string is placed in its exact position by moving the others right.
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <conio.h>
[code]....
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Feb 20, 2015
I need it to search a dynamic array which I build from an input file. When it finds the user-input string, I want it to store the line number, and continue searching, and record all lines that contain the user-input string.
Here is a link to my complete main.cpp, header file, and implementation file. The function I am having trouble with is "Bagger::lineSearch"
[URL] ....
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May 21, 2014
I am trying to understand why i keep getting errors in my code. The errors are after the string is converted in my console window. I have to allocate and delete memory via dynamic array to do the problem.
#include<iostream>
#include<string>
#include<cctype>
using namespace std;
int main() {
string sentence;
int size;
[code]....
I just want to know why the extra characters are at the end of my conversion and how to make them stop.
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Dec 8, 2013
I am trying to alphabetize 3 different strings by comparing the first letter in each one. It will work for the first two names, but when I try to print out the third, I keep getting errors and I don't know why?
Code:
#include <stdio.h>
char personName();
int main() {
personName();
return 0;
[Code] ....
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Feb 11, 2013
I am having troubles with dynamic arrays and pointers. All the errors are of that kind. I think when I am assigning malloc to an array we assign to its address.
Code:
/*Create an array of genes of the large matrix*/
gene_t gene,gene1,gene2;
gene=malloc(INITIAL*sizeof(gene2)); Code:
while(...) {
if (gene_num==current_size){
[Code] .....
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Apr 25, 2014
Class with Pointers and Dynamic Arrays
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Apr 15, 2013
I'm trying to write a function that takes a 32bit address and a data to store at this address.
I'm wanting to take the 32 bit memory address eg 0x12345678 and split it
into 4 x 2 bytes
12, 34, 56, 78
then each of the 4 entries is at most a 256 entry array.eg
FF, FF, FF, FF
So in this example, 0x12 points to 0x34 in the second array, which points to 0x56 in the third array, which finally points to 0x78 in the last array. This last array holds the actual data.
After successfully doing 0x12345678, say I might get a read for 0x1234AABB. So, the first and second pointers already exist, but I then have to create and write to dynamically created arrays.
The arrays need to have all entries set to NULL so that i know whether to follow the pointers to overwrite a previously entered value or create new arrays and pointers.
It all looks good and simple in the pseudo code I've written up but I'm having trouble coding it. I'm currently trying to deal with the first entry case, ie all array elements are NULL, but I'm getting confused with the pointers and creation of new arrays.
void cpu::store(unsigned int mem_add,unsigned int mem_val) {
int first = (mem_address&4278190080)>>24;
int second = (mem_address&16711680)>>16;
int third = (mem_address&65280)>>8;
int fourth= (mem_address&255);
[Code] .....
A1 has been declared as
int* A1[256] ;
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Nov 16, 2013
we are currently covering double pointers and memory allocation. Currently getScrabbleWords is not working. when I compile with commented code (Main() works fine) I get a segmentation fault.
This is the purpose of getScrabbleWords:
char **getScrabbleWords(char **allWords, char letters[]):
This function takes an array of char* values (i.e. strings) representing all the words read from wordlist.txt. Each of these words is tested by callingcanWeMakeIt as a helper function, and pointers to the words that can be made are put into an array, myWords. Note, copies of the words are not made! In order to indicate the end of myWords, we terminate with a NULL pointer. Thus, if N words can be made from letters then myWords should have length N+1.
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Apr 13, 2014
I have the following code here. My questions are:
1. Pointers can be used as pass by reference. When I dynamically allocated memory for array[50] in the run function, does that mean I am changing the size of the pArray in main as well? Or does the scope of array[50] ends with the function run? if so, should I do a delete [] Array inside the run function?
2. When I do delete[] pArray in main, what does it delete? memory for array[50]? or array[100]?
#include <iostream>
using namespace std;
void run(int* Array, int& s) {
s = 50;
Array = new int[s];
[Code] ....
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Feb 28, 2014
I'm trying to create an array of pointers to pointers which will point to array of pointers (to strings) I tried
Code:
int i;
char *string[]={
"my name is dave",
"we like to dance together",
"sunny day",
"hello",
[code]...
the app keeps crashing , I don't know how to make the array-elements to point to another array-elements..
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Dec 21, 2014
I need to use dynamic memory allocation and use pointers to iterate through the arrays that I have already in this program. I am lost, nothing I do works and where to use the pointers. I am just looking for a push in the right direction so I can finish this project and how I can implement pointers in my program.
#include <iostream>
#include <string>
#include <cstdlib>
#include <iomanip>
#include <stdio.h>
using namespace std;
[Code]...
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Jan 4, 2013
I'm writing a program in which I have to use a matrix to represent a file in code. because it's a file, the size of the matrix is undefined, and therefore the matrix has to be dynamic. I found out that my compiler doesn't like dynamic multidimensional arrays, so I was thinking of this matrix as a dynamic (monodimensional) array of other dynamic (monodimensional) arrays. My program (and thus this example) uses unsigned chars.
unsigned char variable=something;
unsigned char**matrix=new unsigned char*[lenghtOfMainArray];
for(int rowNumber=0;rowNumber<lenghtOfArray;rowNumber++)
{
[Code].....
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Mar 6, 2015
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
char * form(char *format, ...);
}
[code]...
So, this is the code i have problem with, as far as i can see, function form actually does the same thing that printf does.It probably puts all of the arguments sent to the function together into one string.
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Mar 6, 2015
I need to create dynamic string by given format(%d,%s,%f,%lf,%c) using variable number of arguments in function. This code gives me an error(main.exe has stopped working):
Code:
#include<stdio.h>
#include<stdarg.h>
#include<string.h>
#include<stdlib.h>
char *form(char *format,...);
char *form(char *format,...)
[Code]...
I assume the error is in functions(itoa,fcvt,ecvt).
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Sep 14, 2014
Is it possible to create a dynamic char array on the fly directly from stdin? I do not want to create a fixed length array before hand and then copy contents of it into a malloc created array.
Code: //[1]
char line[MAX1];
gets(line);
[Code]....
I could do either [1](buffer overflow problem) or [2] and then goto [3]. But both will have a problem if the input is more than the size MAX1(use defined).
Is it possible to do something of the effect of readLine() method of BufferedReader class in Java or the Console.readLine in .NET? Is it possible to peek into stdin and see the size of the input and then creat an array of the same exact size?
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Mar 14, 2015
I need to create dynamic string by given format(%d,%s,%f,%lf,%c) using variable number of arguments in function. This code gives me an error(main.exe has stopped working):
#include<stdio.h>
#include<stdarg.h>
#include<string.h>
#include<stdlib.h>
char *form(char *format,...);
char *form(char *format,...)
[Code] ....
I assume the error is in functions(itoa,fcvt,ecvt).
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Jun 27, 2013
I've got some functions and macros that I want to execute based on a string input that matches the function's name. I came across as this being a possible solution that I'd like to pursue IF it is possible to do. To clarify, I want to be able to look at a string and if the string matches the name of a defined function or macro then it will execute. Is there an effective way to do this (or is it even possible)?
It has to be pretty robust and dynamic given the project's purpose. Basically there's an input file that is being parsed and functions should execute if called upon in the file. I can't simply match strings to their corresponding functions in decision statements, as this isn't robust and isn't scalable.
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Sep 12, 2013
Having some trouble with basic stuff while learning C. My purpose was to flip the pointing order, so it would point to the string from the end to the start. didn't work so well using **str as well.
Code:
#include <stdio.h>
#include <conio.h>
char str_inve(char *ptr);
[Code] .....
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Nov 13, 2013
everything seems to be right in this program except that the puts() function does not print anything.
Code:
/*c program to reverse a string using pointer*/
#include<stdio.h>
#include<conio.h>
#include<string.h>
}
[code]....
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Apr 22, 2014
My teacher has done a very poor job of teaching us anything this year. When he taught us for loops, he wrote one on the board, didn't explain any of it, then said now that you know for loops we can implement them in a code. but anyway, we need to write a code for converting a string to an int and all the examples i find on the internet use pointers but we aren't allowed to use those yet.
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Feb 26, 2014
I am having some trouble tokenizing some strings in C. I am trying to take in a string dynamically and spit print it to the console tokenized using the spaces as delimiters. I have tried using frets() and scant() as well as playing around with pointer values to no avail.
#include <stdio.h>
#include <unistd.h>
#include<string.h>
#include <stdlib.h>
#define MAX_LINE 80
//function prototypes
void printArgs(int argc, char* args[]);
[Code] .....
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