This Program is working on gcc, clang and tcc compilers with modes: -Wall -pedantic but here it is not working properly

Question

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

int main() {
char* str= (char*)malloc(sizeof(char));
str[0]= '\0';
int i=0;
char get;
get=getchar();
while( get!='\0' && get!='\n') {
i++;
if(isupper(get)){
str= (char*)realloc(str, (i+1)* sizeof(char));
str[i-1]= '_';
i++;
}
str= (char*)realloc(str, (i+1)* sizeof(char));
str[i-1]= tolower(get);
str[i]='\0';
get=getchar();
}
puts(str);

return 0;
}

Answer 1

Your program loops until it receives a NULL or a NEWLINE. In SoloLearn, that's breaking. To make this program work, when you input the data to run the script, add a NEWLINE at the end of your data.

Type your word, press ENTER, your cursor goes to the next line. THEN submit it. It will work.

To fix this, you'll need to test the condition differently.

I don't know why - but in SoloLearn, after the end of the characters it starts returning -1. So you can fix your program by testing for -1.

while( get!='\0' && get!='\n' && get!= -1)

NOTE: How I solved this was I added a print statement below the second get=getchar(); line.

printf("%c:%d\n", get, get);

That prints the character being input as well as the integer value of that character.

Answer 2

Jerry Hobby the reason for -1 is that is the value for EOF. Remember that Sololearn's batch script saves your console input into a text file, and then redirects stdin to come from that file. So unless the user enters a null or newline as the last character it will encounter EOF.

while (get!='\0' && get!='\n' && get!=EOF)

Answer 3

Bob_Li I added the print statement mentioned in my comment. It showed -1. I was expecting a newline or null. Surprised me. Printf is the best debugging tool. lol

Answer 4

Brian lol. you are correct sir. Thanks for that clarification. I love the brilliant minds around here.

Answer 5

Jerry Hobby
How did you find out about Sololearn returning -1? This is new to me. Just curious about the method.

Answer 6

Jerry Hobby
sorry I missed something that is explicitly written...😅

Great detective work. Print debugging is also my weapon of choice. Nice and simple.

Answer 7

Brian
yes, that input box have to come from somewhere.

Answer 8

Thank you all for helping me.