Convert input to uppercase in a game - c

Question

I wrote a very simple Hangman game that requests user input then makes the user guess up to six times.
The first letter of the word is always shown and if the user inputs the same letter that has already been uncovered it is not seen as a mistake,
I want to improve my code to make it accept lowercase input if the hangman string consists of Uppercase letters.
For example if the input string is "HELLO" and the user sees this H_____ on the console and he inputs lowecase 'e' then the letter should be uncovered and printed as a capital letter as the input string.
So after the user inputs e the output should look like this HE___
However with the way I implemented it just converts all uppercase Letters to lowercase Letters.
How can I make the code accept lowercase userinput and print out Uppercase user input if a Uppercase letter is in the string?
Thanks for any help
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
int main(void)
{
char hangmanWord[100], tempWord[100];
char hangmanOutput[100];
int wrongTry = 6 , matchFound = 0;
int tries = 0;
int counter = 0 , position = 0, winner, length , i;
char alphabetFromUser;
scanf("%s",hangmanWord);
getchar();
length = strlen(hangmanWord);
for( i = 1; i < length ; i++)
{
hangmanOutput[i] = '_';
hangmanOutput[length] = '\0';
}
for(i = 0 ; i < length ; i++)
{
if(i==0){
printf("%c",hangmanWord[0]);
}
printf("%c",hangmanOutput[i]); //line output
if(i==length-1){
printf("(%d)",tries);
}
}
while(wrongTry != 0) /**while loop for exiting the program when no try left**/
{
matchFound = 0;
putchar('\n');
printf("letter: ");
scanf("%c",&alphabetFromUser);
fflush(stdin);
if (matchFound != 2)
{
for(counter=0;counter<length;counter++) /**for loop to check whether player input alphabet exists or not in the word**/
{
if(hangmanWord[counter]>= 'A' && hangmanWord[counter] <= 'Z'){
hangmanWord[counter] = tolower(hangmanWord[counter]);
}
if(alphabetFromUser==hangmanWord[counter])
{
matchFound = 1;
}//end of if()
}//end of
if(matchFound == 0) /**in case of wrong guess**/
{
wrongTry--;
tries++;
}//en
else
{
for(counter = 0; counter < length; counter++)
{
matchFound = 0;
if(alphabetFromUser == hangmanWord[counter])
{
position = counter ;
matchFound = 1;
}//end of if
if(matchFound == 1)
{
for(i = 0 ; i < length ; i++)
{
if( i == position)
{
hangmanOutput[i] = alphabetFromUser; /**Put the alphabet at right position**/
}
else if( hangmanOutput[i] >= 'a' && hangmanOutput[i] <= 'z' ) /** If the position already occupied
by same alphabet then no need to
fill again EASY!! and continue */
{
continue;
}
else
{
hangmanOutput[i] = '_'; /** Put a underscore at not guessed alphabet position **/
}
}
tempWord[position] = alphabetFromUser; /**put the alphabet in another char array to check with the original word**/
tempWord[length] = '\0';
/**put the NULL character at the end of the temp string**/
winner = strcmp(tempWord+1,hangmanWord+1); /**upon True comparison it will return 0**/
if(winner == 0) /**if the player guessed the whole word right then he/she is the WINNER**/
{
for(i = 0 ; i < length ; i++)
{
if(i==0){
printf("%c",hangmanWord[0]);
}
printf("%c",hangmanOutput[i+1]); //line output
if(i==length-1){
printf("(%d)",tries);
}
}
getchar();
return 0;
}//end of inner if
}//end of outer if
}//end of for loop
}//end of else
} // end of if(matchFound != 2) condition
for(i = 0 ; i < length ; i++)
{
if(i==0){
printf("%c",hangmanWord[0]);
}
printf("%c",hangmanOutput[i+1]); //line output
if(i==length-1){
printf("(%d)",tries);
}
}
getchar();
}
if(wrongTry <= 0) /**if the player can not guess the whole word in 5 chaces**/
{
putchar('\n');
printf("DEAD\n");
return 0;
}
getchar();
return 0;
}

Answer 1

Looking at ascii table, the lower case letters from a-z are from 0x6_, to 0x7_ and the upper case ones from 0x4_ to 0x5_, which means that all we have to do is to toggle off the second bit of the second nibble in order to convert a lowercase letter to an uppercase letter.
(a) a-z are as follows 0110 xxxx, 0111 xxxx
(b) A-Z are as follows 0100 xxxx, 0101 xxxx
Let's assume that we have the character 'a', which is 0110 xxxx. If we use the AND bitwise with 0x5F => 0110 xxxx & 0101 xxxx => 0100 xxxx => 'A'
char upper(char ch) {
return(ch & 0x5F);
}
Now that we have the function, we can use it. Looking at your code, you are checking the hangman array twice in case the user has typed in a lower case letter or a uppercase letter so instead of doing that we could do that once
int32_t right_letter;
int32_t tries;
int32_t win;
right_letter = 0;
/* since one letter is already discovered */
win = length - 1;
while(wrongTry != 0) {
/* read from user */
for(counter = 0; counter < length; ++counter) {
if(hangmanOutput[counter] == '_'){
if(upper(alphabetFromUser) == upper(hangmanWord[counter])) {
hangmanOutput[counter] = hangmanWord[counter];
right_letter = 1;
++win;
}
}
if(win + 1 == length)
/* win */
wrongTry -= !right_letter;
right_letter = 0;
}
I haven't tested the code, but it should work. Try to understand what I have changed and why.
EDIT: #Andrew Henle had mentioned in the comments that the OP hadn't specified the character set, therefore I assumed that It's ASCII.

Answer 2

For an ASCII only input, it is no brainer....Just exploit the fact that char type in C can in fact be used as int and do the maths.
#include <stdio.h>
#include <stdlib.h>
int main(){
char ch;
printf("letter : ");
ch = getc(stdin);
if (ch >= 'a' && ch <= 'z')
ch -=32;
else if (ch >= 'A' && ch <= 'Z')
ch += 32;
printf("output : %c\n", ch);
return 0;
}
Another version is given below. You can replace lower_case and upper_case with any other alphabet you want and boom, it will work.
#include <stdio.h>
#include <string.h>
char convert(char ch){
const char *lower_case = "abcdefghijklmnopqrstuvwxyz";
const char *upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char *p;
if ((p = strchr(lower_case, ch)) != NULL)
return *(upper_case+(p-lower_case));
else if ((p = strchr(upper_case, ch)) != NULL)
return *(lower_case+(p-upper_case));
else
return ch;
}
int main(){
char ch;
printf("letter : ");
ch = getc(stdin);
printf("output : %c\n", convert(ch));
return 0;
}