Hw1_Report

C_programing_language

Name : Ding Chenchao
Number : 5140809061

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F2C.c (modified)

The original code with a heading "Fahrenheit to Centigrade"

#include <stdio.h>
/*print Fahrenheit - Celsius table for fahr = 0,20,...,300;*/
main() {
  float fahr,celsius;
  int lower,upper,step;
  lower = 0;
  upper = 300;
  step = 20;
  fahr = lower;
  printf("Fahrenheit to Centigrade\n");
  while (fahr <= upper) {
    celsius = (5.0/9.0)*(fahr - 32.0);
    printf("%7.0f%14.1f\n",fahr,celsius );
    fahr = fahr + step;
  }
}

Result for compiling & running

In order to compile this sourse code, I use bash to change directory to where it exists, and then compile it with gcc. Finally I run it, and the result is printed on terminal :

rumia@marve:~$ cd C_Hw/
rumia@marve:~/C_Hw$ gcc -o try F2C.c # to compile
rumia@marve:~/C_Hw$ ./try # to test & run
Fahrenheit to Centigrade
      0         -17.8
     20          -6.7
     40           4.4
     60          15.6
     80          26.7
    100          37.8
    120          48.9
    140          60.0
    160          71.1
    180          82.2
    200          93.3
    220         104.4
    240         115.6
    260         126.7
    280         137.8
    300         148.9

Report for modifying & testing

This version is modified from the original sourse code to look more symmentric when executed to print the table. Adding the Heading "Fahrenheit to Centigrade" can be realized by print it before the loop.

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C2F.c

Code for printing the corresponding Centigrade to Fahrenheit table

#include <stdio.h>
/*print Celsius - Fahrenheit table for celsius = 0,20,...,300;*/
main() {
  float fahr,celsius;
  int lower,upper,step;
  lower = 0;
  upper = 300;
  step = 20;
  celsius = lower;
  printf("Centigrade to Fahrenheit\n");
  while (celsius <= upper) {
    fahr = (9.0/5.0)*celsius + 32;
    printf("%8.1f%12.0f\n",celsius,fahr );
    celsius = celsius + step;
  }
}

Result for compiling & running

rumia@marve:~$ cd C_Hw/
rumia@marve:~/C_Hw$ gcc -o try C2F.c # to compile
rumia@marve:~/C_Hw$ ./try # to test & run
Centigrade to Fahrenheit
     0.0          32
    20.0          68
    40.0         104
    60.0         140
    80.0         176
   100.0         212
   120.0         248
   140.0         284
   160.0         320
   180.0         356
   200.0         392
   220.0         428
   240.0         464
   260.0         500
   280.0         536
   300.0         572

Report for modifying & testing

According to the formula :

$$Celsius=\frac{5}{9}\cdot(Fahr-32)$$

I mainly transform the line :

    celsius = (5.0/9.0)*(fahr - 32.0);

into :

    fahr = (9.0/5.0)*celsius + 32;

i.e. :

$$Fahr=\frac{9}{5}\cdot Celsius+32$$

to calculate the fahrenheit given the centigrade, and exchange them in "printf" in order to print a whole "C2F" table.

However I haven't changed the values of "lower","upper" and "step", therefore this program results in printing a Celsius - Fahrenheit table for celsius = 0,20,...,300.

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F2C_1.c

Code employing "for" loop instead of "while" loop

#include <stdio.h>
/*print Fahrenheit - Celsius table for fahr = 0,20,...,300;*/
main() {
  float fahr,celsius;
  printf("Fahrenheit to Centigrade\n");
  for (fahr = 0; fahr <= 300; fahr = fahr + 20) {
    celsius = (5.0/9.0)*(fahr - 32.0);
    printf("%7.0f%14.1f\n", fahr,celsius );
  }
}

Result for compiling & running

rumia@marve:~$ cd C_Hw/
rumia@marve:~/C_Hw$ gcc -o try F2C_1.c
rumia@marve:~/C_Hw$ ./try
Fahrenheit to Centigrade
      0         -17.8
     20          -6.7
     40           4.4
     60          15.6
     80          26.7
    100          37.8
    120          48.9
    140          60.0
    160          71.1
    180          82.2
    200          93.3
    220         104.4
    240         115.6
    260         126.7
    280         137.8
    300         148.9

Report for modifying & testing

To employ "for" loop, I delete the declaration line as well as assignment statements of the variables "lower","upper" and "step", for all of their functions can be realized within "()" following "for" :

  for (fahr = 0; fahr <= 300; fahr = fahr + 20) {

• "fahr = 0" in place of "lower = 0"
• "fahr <= 300" in place of "upper = 300"
• "fahr = fahr + 20" in place of "step = 20"

In the last it turns out the same as code with "while" loop :)

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F2C_2.c

Code for printing the table marked with "Comfortable!"

#include <stdio.h>
/*print Fahrenheit - Celsius table for fahr = 0,20,...,300;*/
main() {
  float fahr,celsius;
  int lower,upper,step;
  lower = 0;
  upper = 300;
  step = 20;
  fahr = lower;
  printf("Fahrenheit to Centigrade\n");
  while (fahr <= upper) {
    celsius = (5.0/9.0)*(fahr - 32.0);
    if (celsius >= 15 && celsius <= 27 ) {
      printf("%7.0f%14.1f\t%s\n",fahr,celsius,"Comfortable!" );
    }
    else
      printf("%7.0f%14.1f\n",fahr,celsius );
    fahr = fahr + step;
  }
}

Result for compiling & running

rumia@marve:~$ cd C_Hw/
rumia@marve:~/C_Hw$ gcc -o try F2C_2.c # to compile
rumia@marve:~/C_Hw$ ./try # to test & run
Fahrenheit to Centigrade
      0         -17.8
     20          -6.7
     40           4.4
     60          15.6   Comfortable!
     80          26.7   Comfortable!
    100          37.8
    120          48.9
    140          60.0
    160          71.1
    180          82.2
    200          93.3
    220         104.4
    240         115.6
    260         126.7
    280         137.8
    300         148.9

Report for modifying & testing

To print additional information at the third column such as "Comfortable!" when the centigrade is ranging from 15 to 27, I choose to use an "if-else" structure to control the output :

    if (celsius >= 15 && celsius <= 27 ) {
      printf("%7.0f%14.1f\t%s\n",fahr,celsius,"Comfortable!" );
    }
    else
      printf("%7.0f%14.1f\n",fahr,celsius );
    fahr = fahr + step;

When the hypothesis of "if" is true, sentences in "{}" is going to be executed. And in order to print an extra string "Confortable!", I add "%s" (format for string type) to the end of "%7.0f%14.1f". However if I compile & run it now, you'll find there is no space between the 2nd and 3rd column. To address this problem I apply "\t" before "%s", and finally it looks better.

When false, the sentence following "else" is to be executed, here I just keep the output the same as F2C.c.