How to read data from file into an array

Question

I have this program to take properties from a data file and input them into calculations into the program. this is my code at the moment but it isn't taking any values into it.. any help is appreciated

float woodcharacStrength(){
    myInfile.open ("strength_classes.txt");     //inputs external file that contains characteristic values for forces parallel to grain.

    for (row = 0; row<3; row++)
        for (col = 0; col<18; col++)            //condition to only read certain rows and columns of the input file
        {
myInfile >> arraylocation[row][col];        //used to define each value of the array
        }

switch(woodType){
    case 'A':
    case 'a': ftk = arraylocation[0][0]; fck = arraylocation[1][0];break;
    case 'B':
    case 'b': ftk = arraylocation[0][1]; fck = arraylocation[1][1];break;
    case 'C':
    case 'c': ftk = arraylocation[0][2]; fck = arraylocation[1][2];break;
    case 'D':
    case 'd': ftk = arraylocation[0][3]; fck = arraylocation[1][3];break;
    case 'E':
    case 'e': ftk = arraylocation[0][4]; fck = arraylocation[1][4];break;
    case 'F':
    case 'f': ftk = arraylocation[0][5]; fck = arraylocation[1][5];break;
    case 'G':
    case 'g': ftk = arraylocation[0][6]; fck = arraylocation[1][6];break;
    case 'H':
    case 'h': ftk = arraylocation[0][7]; fck = arraylocation[1][7];break;
    case 'I':
    case 'i': ftk = arraylocation[0][8]; fck = arraylocation[1][8];break;
    case 'J':
    case 'j': ftk = arraylocation[0][9]; fck = arraylocation[1][9];break;
    case 'K':
    case 'k': ftk = arraylocation[0][10]; fck = arraylocation[1][10];break;
    case 'L':
    case 'l': ftk = arraylocation[0][11]; fck = arraylocation[1][11];break;
    case 'M':
    case 'm': ftk = arraylocation[0][12]; fck = arraylocation[1][12];break;
    case 'N':
    case 'n': ftk = arraylocation[0][13]; fck = arraylocation[1][13];break;
    case 'O':
    case 'o': ftk = arraylocation[0][14]; fck = arraylocation[1][14];break;
    case 'P':
    case 'p': ftk = arraylocation[0][15]; fck = arraylocation[1][15];break;
    case 'Q':
    case 'q': ftk = arraylocation[0][16]; fck = arraylocation[1][16];break;
    case 'R':
    case 'r': ftk = arraylocation[0][17]; fck = arraylocation[1][17];break;
}

    cout <<"The ftk value is: "<< ftk<< endl<<"The fck value is: "<< fck<<endl;

    return ftk;
    return fck;

    myInfile.close();
}

The program flow ends in the first return. Place the file close before the return. Also, you're not doing anything with the switch. — Doktoro Reichard
– Doktoro Reichard, Commented Dec 11, 2013 at 0:45
Sorry im new to c++ i dont really understand.. ill post more of the code up would be grateful for any comments — user3087985
– user3087985, Commented Dec 11, 2013 at 0:50
You have two return statements in a row. Execution comes to the first return statement and returns from the function. Thus the 2nd return and the fclose will never be executed. You compiler should have caught this. Turn up the warning level to maximum. — Thomas Matthews
– Thomas Matthews, Commented Dec 11, 2013 at 0:56

Josh Engelsma · Accepted Answer · 2013-12-11 00:49:45Z

1

for (row = 0; row<3; row++) //you have no open and close braces for this for loop

answered Dec 11, 2013 at 0:49

Josh Engelsma

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1 Comment

paddy Over a year ago

It doesn't look like they are needed. I don't think that switch is meant to be part of the outer loop.

Thomas Matthews · Accepted Answer · 2013-12-11 00:51:23Z

1

Suggestions:
1) Look up std::toupper or std::tolower so you don't have to use both upper and lower case letters in your case statements.

2) Create a index by subtracting letters:

unsigned int index = std::toupper(woodType) - 'A';
ftk = arraylocation[0][index];
fck = arraylocation[1][index];

3) A function can only return one value: ftk or fck. If you want to return more than one value, pass them by reference or put them in a structure and return a copy of the modified structure.

4) No execution flows after a return statement, so your code will never execute the 2nd return statement or the fclose.

answered Dec 11, 2013 at 0:51

Thomas Matthews

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1 Comment

paddy Over a year ago

Don't forget to bounds-check the index.

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