Coders4Fun

This article contains the source code for a c utility that manages a growing string, and a brief explanation of the code.

To obtain this, we make something similar to a c++ class: a struct with associated functions. The functions add characters to the string in the struct, and allocate more memory space when the string is full.

This is usefull when we are working with string with an unknow length (e.g. we are reading a file).

The struct containing the string is the following:

// Struct containing the growing string
typedef struct
{
	// string
	char * text;
	// string length (with zero terminator)
	int length;
	// string capacity
	int capacity;
} growing_string;

The text variable is where the string is allocated, length is the current string lenght and capacity is the memory allocated for the string.

To better understand the difference between length and capacity, look at the next image:

Capacity is the total space allocated for the string, while length is the actual number of character of the string, including the \0 terminator (the special character that close the string). If we add enough characters and the length is greater than the capacity, we need to allocate more memory for the string.

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Main.java

public class Main {

  public static void main(String[] args) {
    System.out.print(Quiz.GetMagicNumber());
  }

}

Quiz.java

public class Quiz {

  static int magicNumber = 3;

  public static int GetMagicNumber()
  {
    return magicNumber;
  }
}

What we need to add in Quiz class to print 5 instead of 3?