C character buffer

buffer.c

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include "buffer.h"

/*
 * Writes a character to the buffer 
 */
void writeToBuffer(Buffer *b, char c, int position)
{
  // Resize the array if needed
  if(position == (b->length - 1))
  {
    b->length *= 2;
    b->buffer = realloc(b->buffer, b->length*sizeof(char));
    if(b->buffer == 0){
      fprintf(stderr, "Failed to allocate memory to buffer\n");
      exit(0);
    }
  }
  b->buffer[position] = c;
  return;
}


/*
 * Finds the number of characters in the buffer
 */
int getLength(Buffer *b)
{
  int i = 0;
  for(i = 0; i < b->length; i++) if(b->buffer[i] == '\0') break;
  return i;
}

/*
 * Converts the case of a single character
 */
void convertCharCaseWithCount(char *c, int *toLower, int *toUpper)
{
  if(isupper(*c))
  {
    *c = tolower(*c);
    ++*toLower;
  }
  else if (islower(*c))
  {
    *c = toupper(*c);
    ++*toUpper;
  }
}

/*
 * Converts the case of a single character
 */
void convertCharCase(char *c)
{
  int i = 0;
  convertCharCaseWithCount(c, &i, &i);
}

/*
 * Converts the case of a buffer
 */
void convertCaseWithCount(Buffer *b, int *toLower, int *toUpper)
{
  int i;
  for(i = 0; i < b->length; i++)
  {
    convertCharCaseWithCount(&(b->buffer[i]), toLower, toUpper);
  }
}

/*
 * Converts the case of a buffer
 */
void convertCase(Buffer *b)
{
  int i = 0;
  convertCaseWithCount(b,&i,&i);
}

/*
 * Sets up a buffer
 */
Buffer* constructBuffer(Buffer *buffer)
{
  // Set the default buffer length
  buffer->length = 20;
  // Allocate the buffer
  buffer->buffer = (char*)malloc(buffer->length);
  if(buffer->buffer == 0)
  {
    fprintf(stderr, "Failed to allocate memory to buffer\n");
    exit(0);
  }
  return buffer;
}

/*
 * Reads a line into a Buffer
 */
void readLine(Buffer *buffer)
{
  // Allocate temporary variables for the while loop
  char c;
  int input_length = 0;
  // While we get characters from stdin
  while((c = getchar()) != '\n') writeToBuffer(buffer, c, input_length++);
  // Add a /0 at the end
  writeToBuffer(buffer, '\0', input_length++);
}

buffer.h

/*
 * Defines a simple String-like type
 */
typedef struct
{
  int length;
  char* buffer;
} Buffer;

/*
 * Writes a character to the buffer 
 */
void writeToBuffer(Buffer *b, char c, int position);

/*
 * Finds the number of characters in the buffer
 */
int getLength(Buffer *b);

/*
 * Converts the case of a single character
 */
void convertCharCase(char *c);

/*
 * Converts the case of a single character
 */
void convertCharCaseWithCount(char *c, int *toLower, int *toUpper);

/*
 * Converts the case of a buffer
 */
void convertCaseWithCount(Buffer* b, int* toLower, int* toUpper);

/*
 * Converts the case of a buffer
 */
void convertCase(Buffer *b);

/*
 * Sets up a buffer
 */
Buffer* constructBuffer(Buffer *buffer);

/*
 * Reads a line from stdin to the buffer
 */
void readLine(Buffer *buffer);