C :: Accessing Values Stored By A Pointer Into Array
Mar 7, 2013
I am writing a C program to access a string into an array from a pointer array in Visual Studio 2010. Program is given below:-
Code:
#include <stdio.h>
#include <string.h>
void main() {
char data_a[6],data_b[6]="ABcde",*ptr;
ptr=&data_b[0];
data_a[0]=*ptr;
printf("%s",a);
}
I am getting some junk character first and then my actual data on console window. I want to where I am getting wrong and how to resolve it.
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Oct 19, 2014
Goal: Write a program that compares the values stored in the first array to the user inputted values in the second array.
In order to fix this error: [URL]...
I had to change my array initialization to one with a star in front of it:
char a1[]={"a","d","b","b","c","b","a","b","c","d","a","c","d","b","d","c","c","a","d","b"};
to:
char *a1[]={"a","d","b","b","c","b","a","b","c","d","a","c","d","b","d","c","c","a","d","b"};
I also changed my 2nd array to one with a star in front of it: char *a2[20];
What does this mean exactly? Putting a star in front of an array?
Also, I am now getting an "unhandled exception" when I try to get input for my 2nd array:
cin>>a2[i];
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Mar 31, 2013
Code:
int arr[10];
int* p = arr;
int (*p2)[10] = &arr;
So, pointer p is a pointer to an array, I can use it to access elements of arr as in *(p+5).
Pointer p2 is a pointer to an array of ten integers. What is it for, how can I use it to access elements of arr?
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Feb 8, 2014
I'm okay with 2-dimensional arrays, but when I get to 3 or more, I can't seem to wrap my head around how to assign and/or pull values from specific parts.
To give an example, let's take the following example:
We know that a player can take up to 5 total quests, and each quest can have a max of 5 tasks.
Let's assume I have the following multi-dimensional array holding all of a players quest data:
quests[0] = 78;// Store the questID
quests[0][0] = 3945;// Store the 1st creature ID
quests[0][1] = 2230;// Store the 2nd creature ID
quests[0][2] = 3045;// Store the 3rd creature ID
quests[0][0][0] = 2;// Store how many needed of the 1st creature
quests[0][1][0] = 5;// Store how many needed of the 2nd creature
quests[0][2][0] = 13;// Store how many needed of the 3rd creature
As we know, the above code can't be done. How do I assign certain values to each specific dimension?
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Feb 12, 2013
I am using pointer to display values of an array but its output is not correct example 23424,0, -323423 etc... whats the problem with my code:
Code:
#include<stdio.h>
#include<conio.h>
int main() {
clrscr();
int arr[10][10],rows,cols;
int* ptr;
[Code] ....
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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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Sep 19, 2013
My specific request is for retrieving values that are stored to a CompactFlash card. I am able to store values (we call them recipes) to the CompactFlash card as .csv file. I just haven't been able to figure out the code to retrieve this information back to the touchscreen.
Code:
// Create a new folder if it doesn't exist
CreateDirectory("/recipes");
//Create the file if it doesn't exist
CreateFile("/recipes/recipe.csv");
//open the file
hfile = OpenFile("/recipes/recipe.csv", 2);
[Code]....
Now with that said, I would like to retrieve these values from the .csv file.
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Sep 23, 2013
This seems like a fairly straight forward assignment. Load up a file that contains a series of int values stored in ASCII and print out the ASCII characters to the console.
The problem I am having is that I am getting the numerical value of bytes ("40" for 10 numerical values, "200" for 50 values). The numbers are generated randomly by another file, but I can control how many numbers are generated. For example, if I type in:
shell% cat tempfile
the output is as follows:
/8?qE?. Y4?(T???a???%@
but when I try to run it with my program:
shell% ./intcat tempfile
the output displayed is:
40
Code:
#include <stdio.h>
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
int main(int argc, char *argv[]){
//check if arguments match
[Code] .....
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May 16, 2013
I need to check my understanding from some questions about strings. How can numeric values stored as Strings be converted to numbers?
a)vector of required numeric data type
b)atoi function in cstdlib library
c)cout statement with required numeric data type
I picked b), I am aware of atoi, atol, and atof as methods to convert, but are there other methods?
What is the purpose of strncat function?
Combines n characters from source string into target string
C++ string provides:
a)convenient way to declare and manage character arrays
b)functions to manipulate strings
c)all of the above
d)none of the above
I picked c)
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May 9, 2013
I have a pointer to a vector of objects, each object has an array and a couple of strings. how to access the data in the objects via the pointer.
Best tree::chooseSplit(vector <pgm> *ptr)
{
Best splits;
cout<<ptr[1].filePath; //not working!!!
}
filepath is a string in the pgm object. i also need to be able to access elements in an array that also exists in pgm.
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Jun 5, 2012
"
#include <stdio.h>
struct datastructure {
char character;
};
void function(struct datastructure** ptr);
[Code] ....
These codes give these errors:
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
These errors are related to
"
*ptr->character='a';
printf("Ptr: %c",*ptr->character);
"
I want to access "character" data inside the structure "trial" by a pointer to pointer "ptr" inside function "function",but I couldn't find a way to do this.
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Apr 7, 2013
I have tried everything and i still can't access pixel RGB values in float format.
I tried vec3b which produces strange characters which i can't covert to float as it says no suitable function exists.
I tried vector<float> RGB;
with RGB = image.at<vector<float>>(row,col);
I get a unhandled exception error.
So whatever i do, if it is syntax correct i get unhandled exception error. If it should work i get this stupid error. I need it for chroma keying.
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Mar 19, 2014
i had a structure as follows:
struct a{
int x;
struct b{
int y;
b *next;
}b;
};
when i try to access as follows:
struct a *a;
a->b=a->b->next;
i got the following error: base operand of ‘->’ has non-pointer type
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Jan 12, 2015
when i compile and run it it gives me the number 0 and not the proper number stored in array.
Code:
#include <stdio.h>
int main()
{
int myArray[11] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
}
[code]....
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Jan 7, 2015
I want to declare a char* array, and then make any future variables declared to be stored in a specific location within the char* array. Is this even possible, and if it is how would I go about doing it. (I plan on storing any primitive data type in it (not classes or structs), and they may signed or unsigned).....
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Mar 3, 2014
For my code, I want the user to enter 4 integers, which get stored in an array. Here are the lines I wrote relevant to this part:
Code:
printf("Enter 4 integers:
");
scanf("%d %d %d %d," &a, &b, &c, &d);
z[4] = { a, b, c, d};
Would this be correct?
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Sep 2, 2013
how to save text stored in an array to a txt file. can sum1 how to save the text in an array to a file/txt file......
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Jan 7, 2015
I want to declare a char* array, and then make any future variables declared to be stored in a specific location within the char* array. Is this even possible, and if it is how would I go about doing it (I plan on storing any primitive data type in it (no classes or structs), and they may signed or unsigned). I want to be able to use the variables like any other variable, I just want the variable's address to be within the char* array.
I am trying to make a program that is similar to a virtual machine and an emulator put together, and it can only run one os (which will be hard-coded into to the program). The reason I wanted to do this is because it would be the easiest way to make sure that all variables in memory are in one contiguous block, that way the part that manages memory wouldn't have to store the locations of each variable (which would have been necessary for the virtual memory manager).
An example of what I am wanting to do is
char* ram [256]; // Address 0x00 to 0xff
// Code to make sure that new variables' addresses are in ram[] if necessary
unsigned short a = 5; // Gets stored at address 0x00
unsigned int b = a; // Gets stored at address 0x00+sizeof(a)
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Nov 23, 2014
So I have an issue with a homework assignment that I am coding. I am attempting to get a function to iterate through an array and search for a number that was stored in an array by the user. So far I can take the number, get the numbers displayed but in my menuChoice2 function, for some reason the program is not confirming whether or not the number is entered, and is only telling me that the number has not been found, instead of confirming that the number is in the array.
Here is my code thusfar:
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
// Variables that are Globally declared
int menuChoice = 0;
int usernum[1000] = { ' ' };
[Code] .....
To be clear I am not getting any errors but something is telling me that the error is in the formatting of menuChoice2.
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Mar 31, 2013
Develop a function that finds the greatest difference between two consecutive elements stored in an array. Develop a 9 element array of doubles to test your code. Print to the screen which two numbers have the greatest difference as well as the value of the difference. Finally include an overloaded version of the function that will work if the array is composed of integers. Include your code used to test this function.
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Jul 26, 2014
I want to access the elements of my array dynamically. So far I've only figured out how to do this manually. if I tried it like this my code would work but there should be a better way right?
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Aug 27, 2014
Write a program that reads in the names and the ages of ten people. Store these data in two arrays (make sure that the entered names are not longer than the array size you choose). Then produce a table of ten lines, with each line giving the name and age of a person along with the (positive or negative) deviation of that person's age from the average age. The code I wrote to fill in the arrays looks as follows
Code:
#include<stdlib.h>
#include<stdio.h>
int main()
{ // begin main()
// array length
[Code]....
When I compile it, it gives me warnings that few of the variables I declared aren't used, but that is not affecting the program at all. When I run the program, it allows me to pass the names and ages into the arrays, but when it comes to displaying them, I'm getting a 'Segmentation fault'. I used very similar code in Java to write the program, and it worked fine so what is the problem with C then?
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Jan 16, 2015
I am trying to retrieve the elements in an array to print them. I am pretty sure I have everything right, but it is not working. There are 5 values in the array {3, 4, 10, 5, 6}, but the first two elements (supposed to be 3,4) are coming out a 0,-2654238590. The last three elements are coming out correct.
void addDynArr(DynArr *v, TYPE val) {
/* FIXME: You will write this function */
assert(v != 0);
//resize if necessary
if(v->size >= v->capacity)
[Code] ....
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Dec 9, 2014
I've been working for some number of days on this code to take information about movies from both a file and the user, store the infos in an array of structs, and at the end, write all the info out to a file. I'm having some problems with an error message reading:
"prog.c:102:11: error: subscripted value is neither array nor pointer nor vector"
this error occurs in many lines (which I will label specifically below -- they are everywhere where I am trying to access/modify an individual element of a struct element of the array).
A few examples of where I am having the problems are lines:
39, 52-55, 70, 72, and 86 (and more of the same exact variety).
I am obviously rather systematically doing something wrong, but I am quite certain all of these are the exact same mistakes.
I pull up also 2 or 3 other errors, but I don't think they are related and should be able to fix them quickly once I work out this conundrum.
#include <string.h>
#include<stdlib.h>
#include <stdio.h>
int moviecount =0;
typedef struct{
int year;
[Code] .....
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Nov 22, 2012
I was wondering if it was possible to access data from an array inside a threaded function after it has finished executing?
Take this example:
Code:
#include <iostream>
#include <boost/thread.hpp>
using namespace std;
[Code]....
After workerFunc has finished, how could I access the array arr? Is there any way to get (3,4,5,6,7) back into main()?
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Aug 4, 2014
I have a contiguous sequence of section headers in a file (all the data in the file is stored in void * data), where each section header is the same size and has the same fields in the same order. So it's laid out like an array.
I have to:
- Use an offset value and the number of section headers variables to identify the location and length of the section header table (these are hdr.offset and hdr.length respectively).
- The offset value shows the distance between the start of the file and the start of the first section header (so I need a pointer to the start of the first section header)
- Apply a typecast to location of the section header table to process it as an array of section headers.
Here is what I have done, but I am getting a segmentation fault. What am I doing wrong? How do I fix this?
typedef struct {
unsigned int name;
unsigned int type;
} SectionHeader;
[Code] ....
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