Print output just beside the user input - c

Question

According to the question, The user needs to enter the no of hours the vehicle is parked and the total charge for the hours should get printed beside it.
for example:
I created this simple program
#include<stdio.h>>
#include<math.h>
float calculateCharges(float hurs);
int main()
{
float hours;//total no of hours vehicle is parked
int i;
printf("%s%10s%10s", "Car", "Hours", "Charges");
for (i = 1; i <= 3; i++)
{
printf("\n%d\t", i);
scanf("%f", &hours);
printf("\t%f\n", calculateCharges(hours));
}
getch();
return 0;
}
float calculateCharges(float hurs)
{
float charges;
hurs = ceil(hurs);
if (hurs >= 24) charges = 10;
else
{
if (hurs <= 3) charges = 2;
else
{
hurs = hurs - 3;
charges = 2 + 0.5*hurs;
}
}
return charges;
}
But now every time I enter hours the charges are getting printed below it instead of beside it. As shown in the image:
Is there is a way to consume the newline after scanf? So that charges can be printed beside the scanf?
I have modified my code this way too, but it didn't make any difference.
printf("%s%10s%10s", "Car", "Hours", "Charges");
for (i = 1; i <= 3; i++)
{
printf("\n%d\t", i);
printf("\t%f\n",(scanf("%f", &hours),calculateCharges(hours)));
}
Let me know if the original question is required. I'm using Visual studio 2017 RC.

Answer 1

You can use something like this:
#include <iostream>
#include <windows.h>
//This will set the position of the cursor
void gotoXY(int x, int y) {
//Initialize the coordinates
COORD coord = {x, y};
//Set the position
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
return;
}
void getCursorXY(int &x, int&y) {
CONSOLE_SCREEN_BUFFER_INFO csbi;
if(GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi)) {
x = csbi.dwCursorPosition.X;
y = csbi.dwCursorPosition.Y;
}
}
I found it here.
As already written in one of the answers this solution is not platform independent.
But i guess there are similar solutions on other platforms and you can easy set the cursor on the position you want.
Example usage in your main:
for (i = 1; i <= 3; i++)
{
printf("\n%d\t", i);
scanf("%f", &hours);
gotoXY( 20, i + 1);
printf("\t%f\n", calculateCharges(hours));
}
Workarounds for scanf can be found here.

Answer 2

scanf_s always generates a new line upon enter and unfortunately other user input capturing platform independent functions I know of (getc & getchar) do so too. Anyway on Windows it could be done using _getch() from conio header.
#include <conio.h>
#include <stdlib.h>
#include <stdio.h>
int getIntFromUser()
{
char readCharacters[10];
int index = 0;
for (int currentChar = _getch(); currentChar != '\r'; currentChar = _getch())
{
if (currentChar == EOF)
{
// Some error that shouldn't occour in your simple homework program
}
if (index > 9)
{
// Another possible error case where you would start to write beyond 'readCharacters' array
}
// We might as well disallow anything but digits, enter & backspace (You don't need anything else, do you?)
if ((currentChar < '0' || currentChar > '9') && currentChar != '\b')
{
continue;
}
else if (currentChar == '\b')
{
if (index > 0)
{
// Delete last character
printf("\b \b");
readCharacters[index] = '\0';
--index;
}
}
else
{
printf("%c", currentChar);
readCharacters[index] = currentChar;
++index;
}
}
if (index == 0)
{
// User pressed enter without having entered a number, let's give him a zero then
return 0;
}
readCharacters[index] = '\0';
int retVal = atoi(readCharacters);
// Worth noting that the value of converted user given string shouldn't be greater than what a signed int can hold
return retVal;
}
int main(int argc, char* argv[])
{
// Unlike scanf_s this will not generate a new line on enter
printf("getIntFromUser() sample (enter a number)\n");
int someValue = getIntFromUser();
printf(" -- This will be printed on the same line. (someValue is %d)\n\n", someValue);
// scanf_s sample
int anotherValue;
printf("scanf_s() sample (Insert a number.)\n");
scanf_s("%d", &anotherValue);
printf("This will be printed on a new line\n\n");
printf("Press any key to exit.");
_getch();
return 0;
}
EDIT
I feel like the above would become less readable if I were to add a comment over every code line. Instead I'm going to paste some blocks of code 1 by 1.
But first about the _getch function: It waits for the user to type something into the console and then returns the user given char as an int. char implicitly converts to int, so you may compare the _getch result to a character as I did many times in getIntFromUser (e.g. if (currentChar == '\b') { ... }).
You should also know about the values a char can hold and what their values are as an int (check out http://en.cppreference.com/w/cpp/language/ascii).
Going by the table the char '0' would be value 48 as an int, which is what _getch would return if the user were to type a 0.
First declare an array/string of 10 elements. Hope you know about them already. In this case the array is basically a chain of 10 elements that are all of type char, which are also referred to as string.
char readCharacters[10];
An indexer for the string is required.
int index = 0;
Below we have the usual for loop that...
1st: creates a variable of type int and assigns the result of _getch to it.
2nd: will determine if the loop shall keep executing. In this case the loop will break when currentChar is not '\r', which is an escape sequence that represents enter as a character.
3rd: will execute stuff inside once and then update currentChar with a new _getch.
for (int currentChar = _getch(); currentChar != '\r'; currentChar = _getch())
Checks if the user input (retrieved via _getch) is smaller than '0' (value 48 as an int) and greater than '9' (value 57 as an int). If either of them is true it will additionally check if the value of currentChar is not '\b' (value 8 as an int), which is the escape sequence for a backslash.
When that additional check evaluated to true as well then the keyword continue is used. Meaning that the rest of the block in the loop is not executed and instead the loop will start at the top again by getting a new user input and evaluating if the loop is to be continued by checking if obtained currentChar was enter.
if ((currentChar < '0' || currentChar > '9') && currentChar != '\b')
{
continue;
}
NOTE: You might want to read the comments on the else statement before you read these.
When the above if statement was false we get to the next if-statement (actually else if) that we see below.
As mentioned above: '\b' is backslash and if this is the user given char as well as string/array index being greater than 0 we move one character backwards in the console by "printing" '\b' and then write an empty character in order to delete what was written at that place previously. That puts us back to the position we were before so we print another backslash. At this point you might wonder why not just go back to the previous line that scanf_s causes, but that won't work. We must also not forget to replace the last string character with a null terminator and then set the index back by 1.
else if (currentChar == '\b')
{
if (index > 0)
{
// Delete last character
printf("\b \b");
readCharacters[index] = '\0';
--index;
}
}
When we hit this point we know that currentChar is something between 48 and 57 ('0' and '9').
_getch told the program what the user's input was, but we cannot see it in the console unless we print it there. So let's do that.
Also append the user's given character to the string as well as incrementing the index by 1.
else
{
printf("%c", currentChar);
readCharacters[index] = currentChar;
++index;
}
Lastly we call the atoi function that will convert our string/array to an integer.
int retVal = atoi(readCharacters);