Visit Our UNIX and Linux User Community


Dynamic memory allocation


 
Thread Tools Search this Thread
Top Forums Programming Dynamic memory allocation
# 1  
Old 08-30-2008
Dynamic memory allocation

Hi,

I am trying to process line by line of a file. But I should not be allocating static allocation for reading the contents of the file. The memory should be dynamically allocated. The confusion here is how do I determine the size of each line, put it into a buffer with the memory allocated with the size of the line?


Is there any optimised way to do this?

Thanks,
Anitha
# 2  
Old 08-30-2008
size of a line means its length right??
# 3  
Old 08-30-2008
Yes, the length of each line.

Suppose I have a file with the lines:
Today is tuesday.
Tomorrow is Wednesday.

I have to find the length of the first line which I can do by character by character reading till I reach a '\n' with a count of the number of characters but then I have to go back to the beginning of the line again to read the contents of the line and put in the buffer which is allocated the number I obtained by the first level of counting.
# 4  
Old 08-30-2008
Quote:
Originally Posted by naan
Yes, the length of each line.

Suppose I have a file with the lines:
Today is tuesday.
Tomorrow is Wednesday.

I have to find the length of the first line which I can do by character by character reading till I reach a '\n' with a count of the number of characters but then I have to go back to the beginning of the line again to read the contents of the line and put in the buffer which is allocated the number I obtained by the first level of counting.
Why dont you construct a buffer of some size say 1024. Initialize the buffer contents with 0. As you read each character put that character into the buffer. Once the line is done, you have the length as well as the contents. Create your new memory with that length and do a memcpy (destination, source, length) to copy the contents.
# 5  
Old 08-30-2008
this wont work for lines that are greater than size 1024

instead, parse through the line and then do a dynamic allocation and copy the contents, free that.

But throughput will suffer here as memory is allocated and deallocated each time for parsing a line. Instead of a big buffer size like 1KB or 2 KB ask Vino suggested can be safely used.
# 6  
Old 08-31-2008
Maybe this will help?
# 7  
Old 09-02-2008
Quote:
Originally Posted by naan
Hi,

I am trying to process line by line of a file. But I should not be allocating static allocation for reading the contents of the file. The memory should be dynamically allocated. The confusion here is how do I determine the size of each line, put it into a buffer with the memory allocated with the size of the line?


Is there any optimised way to do this?

Thanks,
Anitha
Any compelling reason to go for a dynamic solution??
A static solution may not be optimized but a dynamic solution would be expensive in terms of mp units.

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Programming

C++/ROOT Memory Allocation?

Hello, I am new to C++ programming, so I'm still getting a feel for things. I recently wrote a simple C++ program (to be used as a ROOT Macro) to conduct a statistical analysis of a varied version of the Monty Hall problem (code below). Basically, the programs runs a few simple calculations to... (7 Replies)
Discussion started by: Tyler_92
7 Replies

2. Shell Programming and Scripting

memory allocation to a variable

hello all.. i'm a beginner in shell scripting. I need to know what is really happening when we are creating a variable in shell scripting? how memory is allocated for that variable? (3 Replies)
Discussion started by: aarathy
3 Replies

3. Programming

Dynamic Memory Allocation

Hello Guys I have a small confusion in the dynamic memory allocation concept. If we declare a pointer say a char pointer, we need to allocate adequate memory space. char* str = (char*)malloc(20*sizeof(char)); str = "This is a string"; But this will also work. char* str = "This... (2 Replies)
Discussion started by: tene
2 Replies

4. Programming

Memory allocation in C

Hi Experts I need some help in static memory allocation in C. I have a program in which I declared 2 variables, one char array and one integer. I was little surprised to see the addresses of the variables. First: int x; char a; printf("%u %u\n', &x, a); I got the addresses displayed... (2 Replies)
Discussion started by: unx_freak
2 Replies

5. Programming

dynamic allocation vs static allocation in c

i wrote a tiny version of tail command using a large buffer statically allocated but, in a second time, i found another version in which i use a bidimensional array dynamically allocated. here is the first version /*my tiny tail, it prints the last 5 line of a file */ #include<stdio.h>... (4 Replies)
Discussion started by: lucasclaus
4 Replies

6. Programming

Is there a problem with the memory allocation???

I have a scenario like the client has to search for the active server.There will be many servers.But not all server are active.And at a time not more than one server will be active. The client will be in active state always i.e, it should always search for an active server until it gets one.I... (1 Reply)
Discussion started by: vigneshinbox
1 Replies

7. Programming

global variables and dynamic allocation

Hi, is it possible in C to allocate dynamically a global variable?? (3 Replies)
Discussion started by: littleboyblu
3 Replies

8. Programming

Memory allocation problem

I have a program that will fetch some particular lines and store it in a buffer for further operations.The code which is given below works but with some errors.I couldn't trace out the error.Can anybody help on this plz?? #include <stdio.h> #include <stdlib.h> #include<string.h> #define... (1 Reply)
Discussion started by: vigneshinbox
1 Replies

9. Programming

array dynamic allocation

Hi, I have the following problem: i must allocate a dynamic array from a subroutine which should return such array to main function. The subroutine has already a return parameter so i thought of pass the array as I/O parameter. I tried the following program but it doesn't work (segmentation... (11 Replies)
Discussion started by: littleboyblu
11 Replies

10. UNIX for Dummies Questions & Answers

memory allocation

I would like to know how I could allocate some more memory to a process. Please note that I am not the root user. (1 Reply)
Discussion started by: sagar
1 Replies

Featured Tech Videos