Writing ctype.h std library - additional function added: capitalize

customfunctions.c

#include <stdio.h>

int isdigit(int);
int islower(int);
int isupper(int);
int tolower(int);
int toupper(int);
int isspace(int);
int isprint(int);
void capitalize(char s[]);

int main(void)
{
  char s[] = "Lorem ipsum mr. Cat";

  int i;

  for (i = 0; s[i] != '\0'; ++i)
    if (!isspace(s[i]) && islower(s[i]))
      s[i] = toupper(s[i]);

  printf("Upped string: %s\n", s);

  for (i = 0; s[i] != '\0'; ++i)
    if (!isspace(s[i]) && isupper(s[i]))
	s[i] = tolower(s[i]);

  printf("Lowed string: %s\n", s);

  capitalize(s);

  printf("New string: %s", s);

  return 0;
}

int isdigit(int c)
{
  return c >= '0' && c <= '9';
}

int islower(int c)
{
  return c >= 'a' && c <= 'z';
}

int isupper(int c)
{
  return c >= 'A' && c <= 'Z';
}

int tolower(int c)
{
  return c + 'a' - 'A';
}

int toupper(int c)
{
  return c - 'a' + 'A';
}

int isspace(int c)
{
  return c == ' ';
}

int isprint(int c)
{
  return c >= 32 && c <= 126;
}

void capitalize(char s[])
{
  int i;
  i = 0;

  while (s[i] != '\0') {
    if (s[i] != ' ' && s[i - 1] && s[i - 1] == ' ') {
      s[i] = toupper(s[i]);
    } else if (s[i] != ' ' && !s[i - 1])
      s[i] = toupper(s[i]);
    ++i;
  }
}