Program to calulate the square of number

I have made a C code that can replace the comma in a number by a decimal point. But my problem is that I also want to calculate the square of the number. Do you have any idea regarding the same?

Code:

---

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

int main (int argc, char *argv[])
{
  char x = 0;

  while (x != '\n')
  {
    scanf ( "%c", &x);
    if (x == ',')
        printf (".");
    else
        printf ( "%c", x);
  }
return 0;
}

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I don't know much about C coding but I think you should use the atoi () function. It converts any ASCII variable to integer value.

Thank you XSI for your answer, and I changed the code a bit according to your opinion. But the function atoi () gives me part of the number (just the whole number) whereas I also want to retrieve the decimal.

Code:

---

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

int main ()
{
char t[10]={0};
int i;
scanf ( "% s", t);
for (i = 0; i <10; i + +)
{
if (t ==',')
t ='.';
}
printf ( "% s \ n", t);
printf ( "% d", atoi (t));
return 0;
}

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If you want both the whole number and the numbers after comma (i.e. decimal number) then use the function atof () and not atoi (). atof results in floating values.