' char* strInput =(char*) malloc(sizeof(char));
int ch;
int letNum = 0;
while((ch = getchar()) != EOF){
letNum++;
strInput = (char*)realloc(strInput,letNum*sizeof(char));
*(strInput + letNum - 1) = ch;
}
printf("\n");
printf("%s\n",strInput);
free(strInput);`
This is the contents of main in a program I wrote that takes an undefined number of chars and prints the final string. I don’t understand why but it only works if I press ctrl+D twice, and only once if I press enter before.
does anyone get what’s going on? And how would you have written the program?
It’s due to the way getchar() and console input work. When you enter “abcdCTRL+D” on the keyboard, here’s what happens:
Think about this scenario: What happens if you only enter “abcd” and not press anything else? The program will still be waiting for more input. It needs to receive a signal telling it to stop with the input and proceed with the code execution. But if you press enter, it won’t automatically add a new line to the string, because the new line character is still in the input buffer.
This guy is right. I saw OP’s post but I did not have enough time to reply at the time. I came back to reply to OP’s post, but you are already right.
Thanks a lot for your answer. This might be because of my shallow understanding of how a buffer works, but I don’t understand why EOF isn’t consumed by getchar() when the other bytes are consumed. Isn’t a char just a number and EOF too (-1 I think)? I probably should try and understand buffers more