[Courses] lesson 8 calculator - improved

[Eugene Teo]

hi guys,

you might further improve it by writing a postfix calculator :)

1 2 + 
=> 3
1 2 3 + -
=> 0
1 2 3 4 5 + - * +
=> 5

I wrote for one of my old lab for a module last time. It is more
fun than writing the calculator program below :)

Have fun.

Eugene

<quote who="anca14 at anca14.ro">
>    buu :)
> i've modified the calculator program from lesson 8. 
> now, when the user types something else instead of
> a number, the program outputs an error message and 
> then exits:
> 
> ## first, calc-v1.1 asks a number between 0 and 6.
>  - if the input is not a number, it does smth like
>    this:
> - - - - - - - - - - - - - - - - - - - - - - - - - 
> forevah# ./calc-v1.1 
> 
> choose operation [ chacter != number to exit :)] 
> 
> 0 - add      1 - substract   2 - multiply   3 - divide
> 4 - square   5 - cube        6 - square root 
> 
> operation: a
> incorrect key
> - - - - - - - - - - - - - - - - - - - - - - - - - -
> 
>  - if the input is a number between 7 and 9:
> - - - - - - - - - - - - - - - - - - - - - - - - - -
> forevah# ./calc-v1.1
> 
> choose operation [ chacter != number to exit :)]
> 
> 0 - add      1 - substract   2 - multiply   3 - divide
> 4 - square   5 - cube        6 - square root 
> 
> operation: 8
> 0 - add      1 - substract   2 - multiply   3 - divide
> 4 - square   5 - cube        6 - square root 
> 
> operation: 
> - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>   the loop ends when is typed a number between 0 and 6
>   or a chacter that is not a number
> 
> ## after the first step, the program asks two numbers.
>   if one of them is not a number, it displays "incorrect
>   key" and exits.
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
> forevah# ./calc-v1.1
> 
> choose operation [ chacter != number to exit :)]
> 
> 0 - add      1 - substract   2 - multiply   3 - divide
> 4 - square   5 - cube        6 - square root 
> 
> operation: 0
> enter the first number: 23
> enter the second number: fd
> incorrect key
> - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> - 
> 
> i guess calc-v1.1 ain't *buggy* anymore :)
> 
> here is the source code:
> 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 
> // calc-v1.1
> 
> // anca14
> 
> #include <stdio.h>
> #include <math.h>
> #include <stdlib.h> //needed for atof() and atoi()
> 
> // function prototype
> int check_number();
> 
> // global variable
> int operator;
> 
> // asks a character, puts it in a string, and calls
> check_number
> // to verify if it's a number; uses atoi() to convert
> it to integer
> int operation(void)
> {
>    char operator_check[2];
>     
>    puts("\nchoose operation [ chacter != number to exit
> :)]\n");
>    do  
>    {
>       puts("0 - add      1 - substract   2 - multiply  
> 3 - divide");
>       puts("4 - square   5 - cube        6 - square
> root \n");
>          printf("operation: ");
>          scanf("%s",operator_check);
> 
>          check_number(operator_check);
>          operator=atoi(operator_check);
> 
>    } while (operator <0 || operator >6);
> 
> return operator;
> }
> 
> 
> // checks if the input character is a number;
> // if it isn't, displays an error message and
> // exits the program.
> int check_number(char string[])
> {
>    int i;
>    char tester;
> 
>    for(i=0;i<strlen(string);i++)
>       {
>       tester=string[i];
>       if (tester=='0' || tester=='1' || tester=='2' ||
>           tester=='3' || tester=='4' || tester=='5' ||
>           tester=='6' || tester=='7' || tester=='8' ||
>           tester=='9')
>          continue;
>       else
>          {
>          printf("incorrect key\n");
>          exit(1);
>          }
>       }
>    return 0;
> }
> 
> 
> 
> // addition, substraction, etc.
> float add (float x, float  y)
>    {
>    return ( x + y );
>    }
> float  sub (float x, float y)
>    {
>    return (x-y);
>    }
> float  mul (float x, float y)
>    {
>    return (x*y);
>    }
> float divi (float x, float y)
>    {
>    return (x / y);
>    }     
> float square(float x)
>    {
>    return ( (float) pow(x, 2));
>    }
> float square_root(float x)
>    {   
>    return ( (float) sqrt(x));
>    }
> float cube (float x)
>    {
>    return  ( (float) pow(x, 3));
>    }
> 
> 
> 
> int main(void)
> {
> 
>    char xf[1000],yf[1000];
>    float x,y;
>    
>    operation();
> 
>    printf("enter the first number: ");
>    scanf("%s",xf);
>    x=atof(xf);
>    check_number(xf);
> 
>    printf("enter the second number: ");
>    scanf("%s",yf);
>    y=atof(yf);
>    check_number(yf);
> 
>    switch (operator)
>       {
>       case 0:
>          printf("\n%.2f + %.2f =
> %.2f\n\n",x,y,add(x,y));
>          break;
>       case 1:
>          printf("\n%.2f - %.2f =
> %.2f\n\n",x,y,sub(x,y));
>          break;
>       case 2:
>          printf("\n%.2f * %.2f =
> %.2f\n\n",x,y,mul(x,y));
>          break;
>       case 3:
>          printf("\n%.2f / %.2f =
> %.2f\n\n",x,y,divi(x,y));
>          break;
>       case 4:
>          printf("\nsquare (%.2f) = %.2f
> \n",x,square(x));
>          printf("square (%.2f) = %.2f\n\n",y,square(y));
>            square(x);
>          break;
>       case 5:
>          printf("\ncube(%.2f) = %.2f \n",x,cube(x));
>          printf("cube(%.2f) = %.2f \n\n",y,cube(y));
>          break;
>       case 6:
>          printf("\nsquare root (%.2f) = %.2f
> \n",x,square_root(x));
>          printf("square root (%.2f) = %.2f
> \n\n",y,square_root(y));
>          break;
>       // default is not needed beacause of the
> conditions
>       // i've put for the operation option.
>       // see-> while (operator <0 || operator >6);
>       }
>     return 0;
>    }
> 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 
>    that's all, falks.
>    peace ;)
>   
>       anca m. holban
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main(i){putchar(182623909>>(i-1)*5&31|!!(i<7)<<6)&&main(++i);}