Char arrays and file input and out put Update!

nathansetokaiba (8)
So here the story I trying to create a program that will read a file and based on the file info . It choice the correct switch statement and does the assigned function.


The compiler report no errors so I assume it all logic errors on my part. When I run program it does only first file input and ends . I'm sure it something to do with fopen and fscanf. I just cant figure what .


example of file input

+ 2 -4
+ 99 5
+ 55 32
Q




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

# define FILENAME "CommandsProj1.txt"

void Adding_Integer ( FILE * Calculatorfile );


int main()
{



    FILE *Calculatorfile;
    Calculatorfile = fopen( FILENAME, "r");

    char StoredCommand = 'Q';

    if ( Calculatorfile == NULL ) // Confirm access to file
        {
         printf("Error opening file!\n\n\a");
         printf(" Make sure file is in default location\n\n " );
         return 1; // return 1 instead of 0 to state program has error
        }

    printf(" Program is running now\n\a ");


    do {

        fscanf( Calculatorfile ,"%c  " , &StoredCommand);

        switch( StoredCommand )
        {
            case '+' : Adding_Integer (Calculatorfile);

            break;
           // case '-' : Subtraction_Integer();
            //break;
            //case '*' : Multiplication_ Integer();
            //break;
            //case '/' : Divisions_Interger();
            //break;

            case 'Q' :
            break;

            }

            rewind(Calculatorfile);

    } while( StoredCommand  == 'Q');


    fclose(Calculatorfile);

    return 0;
}

void Adding_Integer(FILE * Calculatorfile )
{
    int Addvalue1 = 0;
    int Addvalue2 = 0;
    int sum = 0;

    fscanf( Calculatorfile ,"%i%*c%i " , &Addvalue1 , &Addvalue2 );

    sum = Addvalue1 + Addvalue2 ;

    printf(" The sum of %i + %i = %i \n " , Addvalue1 , Addvalue2 , sum );
    fprintf(Calculatorfile ," The sum of %i + %i = %i \n " , Addvalue1 , Addvalue2 , sum ) ;
}
Last edited on
krakissi (13)
One thing you can do to improve predictability of your code is replace fscanf with getc().
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#include <stdio.h>

int main(){
        char c=0;

        printf("Enter some text:\n> ");
        while(1){
                c=getc(stdin); //Get a character
                if(c=='\n')break; //End of a line? Break!
                printf("%c ",c); //Print the character.
        }

        return 0;
}
Last edited on
S G H (2638)
Tip: } while( StoredCommand == 'Q');
blackcoder41 (1426)
Just like EssGeEich said, try
while( StoredCommand != 'Q');

but that may create an infinite loop since you are calling
rewind(Calculatorfile);

another is you are trying to write to the file
fprintf(Calculatorfile ," The sum of %i + %i = %i \n " , Addvalue1 , Addvalue2 , sum ) ;

if you want to be able to read and write, try to open it with r+ flag
Calculatorfile = fopen( FILENAME, "r+");

Hope that helps..
S G H (2638)
What about getting a line at a time and using sscanf?
Like this:
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while(!feof(CalculatorFile))
{
    char Buffer[256];
    if(!fgets(Buffer,256,CalculatorFile)) // fgets returns 0 when EOF or Error occurs
        break;
    switch(Buffer[0]) // Check the first char in the current line
    {
        case '+': // If it's '+' ...
            Add(Buffer);
    }
}

And in "Add" function, do something like this:
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void Add(const char * Line)
{
    int Operator1 = 0;
    int Operator2 = 0;
    sscanf(Line,"+ %d %d",&Operator1, &Operator2); // It's like a scanf from a string, so a sscanf.
    printf("Result of %d * %d = %d",Operator1, Operator2,Operator1*Operator2);
}
nathansetokaiba (8)
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

    void Add(  FILE *Calculatorfileoutput ,const char * Line );
    void Multiply ( FILE * Calculatorfileoutput , const char * Line);
    void Subtract (FILE * Calculatorfileoutput , const char * Line);
    void Divide (FILE * Calculatorfileoutput , const char * Line);
    void Changecase_UP (FILE * Calculatorfileoutput , const char * Line);
    void Changecase_Down (FILE * Calculatorfileoutput , const char * Line);
    void PrintKD (FILE * Calculatorfileoutput , const char * Line);
    void PrintRR (FILE * Calculatorfileoutput , const char * Line);
    void Separate (FILE * Calculatorfileoutput , const char * Line);
    void Help (FILE * Calculatorfileoutput , const char * Line);
    void Quit (FILE * Calculatorfileoutput , const char * Line);


int main ( void )
{

    FILE *Calculatorfile;
    Calculatorfile = fopen( "input.txt", "r");

    FILE *Calculatorfileoutput;
    Calculatorfileoutput = fopen("output.txt" , "w");



        while(!feof(Calculatorfile))
        {
            char Buffer[256];
            if(!fgets(Buffer,256,Calculatorfile)) // fgets returns 0 when EOF or Error occurs
            {
               break;
            }


            switch(Buffer[0]) // Check the first char in the current line
            {
                case '+' :
                 Add(  Calculatorfileoutput , Buffer );
                 break;

                case '*' :
                 Multiply ( Calculatorfileoutput , Buffer );
                 break;

                case '-' :
                 Subtract (Calculatorfileoutput , Buffer );
                 break;

                case '/' :
                 Divide (Calculatorfileoutput , Buffer );
                 break;

                case 'C' :
                 Changecase_UP (Calculatorfileoutput , Buffer );
                 break;

                case 'c' :
                 Changecase_Down (Calculatorfileoutput , Buffer );
                 break;

                case 'P' :
                 PrintKD (Calculatorfileoutput , Buffer );
                 break ;

                case 'R' :
                 PrintRR (Calculatorfileoutput , Buffer );
                 break;

                case 'S' :
                 Separate (Calculatorfileoutput , Buffer );

                case 'H' :
                 Help (Calculatorfileoutput , Buffer );
                 break;
                //case 'Q' :
                 //Quit (Calculatorfileoutput , Buffer );
                 //break;

                //default :

                 // some command
            }

            rewind(Calculatorfile);
        }



        fclose(Calculatorfile);
        fclose(Calculatorfileoutput);

        return 0 ;

}

void Add( FILE *Calculatorfileoutput ,const char * Line )

{

    int Operator1 = 0;
    int Operator2 = 0;

    sscanf(Line,"+ %d %d\n",&Operator1, &Operator2); // It's like a scanf from a string, so a sscanf.
    printf("Result of %d + %d = %d\n",Operator1, Operator2,Operator1+Operator2);
    fprintf( Calculatorfileoutput,"Result of %d + %d = %d\n",Operator1, Operator2,Operator1+Operator2);

}

void Multiply ( FILE * Calculatorfileoutput , const char * Line)
{
    int Operator1 = 0;
    int Operator2 = 0;

    sscanf(Line,"- %d %d\n",&Operator1, &Operator2); // It's like a scanf from a string, so a sscanf.
    printf("Result of %d - %d = %d\n",Operator1, Operator2,Operator1-Operator2);
    fprintf( Calculatorfileoutput,"Result of %d - %d = %d\n",Operator1, Operator2,Operator1-Operator2);
}

void Subtract (FILE * Calculatorfileoutput , const char * Line)
{
    int Operator1 = 0;
    int Operator2 = 0;

    sscanf(Line,"* %d %d \n",&Operator1, &Operator2); // It's like a scanf from a string, so a sscanf.
    printf("Result of %d * %d = %d \n",Operator1, Operator2,Operator1* Operator2);
    fprintf( Calculatorfileoutput,"Result of %d * %d = %d \n",Operator1, Operator2,Operator1*Operator2);
}
void Divide (FILE * Calculatorfileoutput , const char * Line)
{
    int Operator1 = 0;
    int Operator2 = 0;

    sscanf(Line,"/ %d %d \n",&Operator1, &Operator2); // It's like a scanf from a string, so a sscanf.
    printf("Result of %d / %d = %d \n",Operator1, Operator2,Operator1 / Operator2);
    fprintf( Calculatorfileoutput,"Result of %d * %d = %d\n",Operator1, Operator2,Operator1/Operator2);

}
void Changecase_UP (FILE * Calculatorfileoutput , const char * Line)
{
    char UP_Word[256];

    sscanf(Line,"C %s\n", UP_Word ); // It's like a scanf from a string, so a sscanf.


    printf("UPPER CASE : %s\n", strupr(UP_Word ) );
    fprintf( Calculatorfileoutput,"UPPER CASE : %s \n", strupr(UP_Word ) );

}
void Changecase_Down (FILE * Calculatorfileoutput , const char * Line)
{
    char down_Word[256];

    sscanf(Line,"C %s\n", down_Word ); // It's like a scanf from a string, so a sscanf.


    printf("lower case : %s\n", strupr(down_Word ) );
    fprintf( Calculatorfileoutput,"lower case : %s \n", strlwr(down_Word ) );

}
void PrintKD (FILE * Calculatorfileoutput , const char * Line)
{

}
void PrintRR (FILE * Calculatorfileoutput , const char * Line)
{

}

void Separate (FILE * Calculatorfileoutput , const char * Line)
{
      char String_Separate [256];

      sscanf(Line , "S %s" , String_Separate );

      char * PtrtoString;

      PtrtoString = strtok (String_Separate," ");
      while (PtrtoString != NULL)
      {
        printf ("%s ",PtrtoString);
        fprintf( Calculatorfileoutput,"%s" ,PtrtoString);
        PtrtoString = strtok (NULL, " ");
      }

}


void Help (FILE * Calculatorfileoutput , const char * Line)
{

    printf(  " \t + i j [Integer Add]  Add integers i and j and print out result \n "
             " \t * i j [Integer Multiply]  Multiply integers i and j and print out result \n "
             " \t - i j [Integer Subtract ]  Subtract integer j from i and print out result \n "
             " \t / i j [Integer Divide ]  Divide integer i by j and print out result of integer division \n "
             " \t C Ch [Character Case Change ]  Change character Ch to uppercase and print it out \n "
             " \t c Ch [Character Case Change]  Change character Ch to lowercase and print it out \n "
             " \t P i k [Print k-th Digit ]  Print out the k-th digit of integer i \n "
             " \t R x i [Round Reals ]  Round double value x to i decimal places \n "
             " \t S x [Separate ]  Separate out the sign, integer part and fractional part of double value x \n "
             " \t H [Help ]  Print a short synopsis of all the available commands \n "
             " \t Q [Quit ]  Quit \n " );

     fprintf( Calculatorfileoutput  ," \t + i j [Integer Add]  Add integers i and j and print out result \n "
             " \t * i j [Integer Multiply]  Multiply integers i and j and print out result \n "
             " \t - i j [Integer Subtract ]  Subtract integer j from i and print out result \n "
             " \t / i j [Integer Divide ]  Divide integer i by j and print out result of integer division \n "
             " \t C Ch [Character Case Change ]  Change character Ch to uppercase and print it out \n "
             " \t c Ch [Character Case Change]  Change character Ch to lowercase and print it out \n "
             " \t P i k [Print k-th Digit ]  Print out the k-th digit of integer i \n "
             " \t R x i [Round Reals ]  Round double value x to i decimal places \n "
             " \t S x [Separate ]  Separate out the sign, integer part and fractional part of double value x \n "
             " \t H [Help ]  Print a short synopsis of all the available commands \n "
             " \t Q [Quit ]  Quit \n " );



}
/*void Quit (FILE * Calculatorfileoutput , const char * Line)
{

   if ( )

*/
nathansetokaiba (8)
Thanks everyone for your input really ! That said I posted the updated code .



I did try to change the while loop to 

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do{

}while (StoredCommand!= 'Q');


and it did indeed create inf loop like you said
blackcoder41. My computer almost crash .


For some reason it didn't store the results . I almost went mad

right now I trying to figure out how to quit the program when it encounter q

and what do mean by

P i k [Print k-th Digit ] Print out the k-th digit of integer i


The sample input of this program will encounter is below

JP
+ -3 4
+ -4 -71
- 10 2
- -41 -7
H
* 3 -4
* 2 2
/ 141 13
/ 14 -3
H
c F
C g
P 2134 3
R 3.141500000 2
R 3.141500000 3
R 0.010157 2
S -3.141500
S 31.41500
Q
H
blackcoder41 (1426)
1. again don't call rewind(Calculatorfile); (remove it)

2. remove extra space " \t Q [Quit ] Quit \n" );

3. for lowercase change C to c sscanf(Line,"C %s\n", down_Word );

4. your Subtract and Multiply function got mixed up (interchanged)

5. P i k [Print k-th Digit ] - i represent the integer k represents the index. so in your example 
P 2134 3
you should print 4
char* i= "2134";
int k = 3;
print (i[k]); /* this prints 4 */

6. for separating the integer and decimal part. use the function modf
http://www.cplusplus.com/reference/clibrary/cmath/modf/

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