Thread: Return statement is NOT exiting the function!!!

Originally Posted by Matticus

If you're still encountering the same problem you described initially, then perhaps it would be best for you to create a dummy "main()" function which calls your function and still exhibits the behavior you're seeing, and post it up here. This way, others would be able to compile it and perhaps be able to offer better explanations.

As requested. and YES I UNDERSTAND "IM USING MALLOC and wrong practice blah blah blah" but honestly can we please keep the criticism constructive pertaining to the error itself.

Code:

#include <iostream>
#include <fstream>
#include <stdlib.h>
#include <cmath>
#include <stdio.h>
#include <string>
#include <cstring>

#define ERROR_LOW_WAGON_WEIGHT 101
#define ERROR_HIGH_WAGON_WEIGHT 102
#define ERROR_HIGH_GRADIENT 103

using namespace std;

float ceiling(float unrounded, float increment)
{
    float remainder = fmod (unrounded, increment);
    int quotient = unrounded/increment;
    if (remainder == 0)
        return (unrounded);
    else if (remainder != 0)
        return (quotient*increment + increment);
}

char* tokenizer (string inputstream)
{
    if (inputstream != "NULL")
    {
        char* cstringcpy = (char*)malloc (50 * sizeof(char));
        const char* cstr = inputstream.c_str();
        strcpy(cstringcpy,cstr);
        char* wordptr = (char*)malloc (50 * sizeof(char));
        wordptr = strtok(cstringcpy,"\t");
        return wordptr;
    }
    else
    {
        char* cstringcpy = (char*)malloc (50 * sizeof(char));
        const char* cstr = inputstream.c_str();
        strcpy(cstringcpy,cstr);
        char* wordptr = (char*)malloc (50 * sizeof(char));
        wordptr = strtok(NULL,"\t");
        return wordptr;
    }

}

double slot_capacity_required (double volume_per_month, double tons_per_wagon, double wagons_per_train, double operating_weeks_per_year)
{
    return (volume_per_month/(tons_per_wagon * wagons_per_train)) * 12 / operating_weeks_per_year;
}

double wagons_required (double slot_capacity_required, double turn_around_time, double wagons_per_train)
{
    return ceiling((slot_capacity_required/(168/turn_around_time))*wagons_per_train, wagons_per_train);
}

double tons_per_axle (double tons_per_wagon)
{
    return tons_per_wagon/4;
}

double train_tons_to (double tons_per_wagon, double wagons_per_train, double wagon_weight)
{
    return (tons_per_wagon + wagon_weight) * wagons_per_train;
}

double train_tons_from (double wagons_per_train, double wagon_weight)
{
    return (wagon_weight) * wagons_per_train;
}


int locomotives_required (double tons_per_wagon, double train_tons, double gradient)
{
    double tons_per_axle_variable = tons_per_axle(tons_per_wagon);
    ifstream ifs;
    ifs.open ("C:\\LoadTables.txt", std::ofstream::out | std::ofstream::app);
    string lineread;
    getline (ifs, lineread);
    char* wordptr = tokenizer(lineread);
    int number = atoi(wordptr);
    int j;
    int locomotive_counter = 0;
    if (tons_per_axle_variable < number)
        return ERROR_LOW_WAGON_WEIGHT;
    for (int i = 1; *wordptr != 'EOF'; i++) //select the correct table
    {
        wordptr = tokenizer("NULL");
        if (tons_per_axle_variable < atof(wordptr))
            for (j = 1; j <= 18; j++)
            {
                getline (ifs, lineread);
                if (gradient == atof(tokenizer(lineread)))
                    for (int k = 0; k <= 6; k++)
                    {
                       locomotive_counter++;
                        if (train_tons <= atof(tokenizer("NULL")))
                            return locomotive_counter; // this used to return the value 3 that I used just as an example. But in reality I use the variable locomotive_counter
                    }
            }
            if (j == 19)
                return ERROR_HIGH_GRADIENT;
        else
        {
            getline(ifs,lineread);
            while (lineread != "")
                getline(ifs,lineread);
            getline(ifs,lineread);
            wordptr = tokenizer(lineread);
        }
    }
    if (*wordptr == 'EOF')
        return ERROR_HIGH_WAGON_WEIGHT;
}

int main ()
{
    int output = locomotives_required (55, 2986, 13);
    cout<< output;
    return 0;
}

And then you guys might need to save a text file called LoadTables.txt in your C drive. The contents of the file are as follows (copy and paste it in your text file:

2 7
GC 0 1 2 3 4 5 6
1 0 290 590 880 1170 - -
2 0 340 680 1020 1360
3 0 390 770 1160 1400
4 0 430 860 1290 1400
5 0 470 940 1400
6 0 510 1010 1400
7 0 540 1090 1400
8 0 580 1170 1400
9 0 610 1220 1400
10 0 670 1340 1400
11 0 720 1400
12 0 770 1400
13 0 820 1400
14 0 860 1400
15 0 960 1400
16 0 1090 1400
17 0 1190 1400
18 0 1230 1400

7 12.5
GC 0 1 2 3 4 5 6
1 0 340 690 1030 1380 - -
2 0 410 820 1230 1630
3 0 470 940 1410 1880
4 0 530 1060 1590 2120
5 0 590 1180 1770 2360
6 0 650 1290 1940 2500
7 0 700 1400 2110 2500
8 0 770 1530 2300 2500
9 0 810 1620 2430 2500
10 0 910 1820 2500
11 0 1010 2010 2500
12 0 1100 2190 2500
13 0 1180 2370 2500
14 0 1270 2500
15 0 1490 2500
16 0 1810 2500
17 0 2080 2500
18 0 2210 2500

12.5 17
GC 0 1 2 3 4 5 6
1 0 360 720 1080 1430 - -
2 0 430 850 1280 1710
3 0 490 990 1480 1980
4 0 560 1120 1680 2240
5 0 620 1250 1870 2500
6 0 690 1380 2060 2750
7 0 750 1500 2250 3000
8 0 820 1650 2470 3290
9 0 870 1740 2610 3400
10 0 990 1980 2960 3400
11 0 1100 2200 3300 3400
12 0 1210 2420 3400
13 0 1310 2630 3400
14 0 1420 2830 3400
15 0 1700 3400
16 0 2120 3400
17 0 2480 3400
18 0 2680 3400

17 19
GC 0 1 2 3 4 5 6
1 0 360 730 1090 1460 - -
2 0 430 870 1300 1740
3 0 500 1010 1510 2010
4 0 570 1140 1710 2290
5 0 640 1280 1920 2550
6 0 700 1410 2110 2820
7 0 770 1540 2310 3080
8 0 850 1690 2540 3390
9 0 900 1790 2690 3590
10 0 1020 2040 3060 3800
11 0 1140 2280 3420 3800
12 0 1260 2510 3770 3800
13 0 1370 2740 3800
14 0 1480 2960 3800
15 0 1790 3590 3800
16 0 2260 3800
17 0 2680 3800
18 0 2900 3800

19 20
GC 0 1 2 3 4 5 6
1 0 370 730 1100 1460 - -
2 0 440 870 1310 1750
3 0 510 1010 1520 2030
4 0 580 1150 1730 2300
5 0 640 1290 1930 2570
6 0 710 1420 2130 2840
7 0 780 1550 2330 3100
8 0 850 1710 2560 3420
9 0 910 1810 2720 3620
10 0 1030 2060 3090 4000
11 0 1150 2310 3460 4000
12 0 1270 2540 3820 4000
13 0 1390 2780 4000
14 0 1500 3000 4000
15 0 1820 3650 4000
16 0 2310 4000
17 0 2740 4000
18 0 2980 4000

Turn on warnings; DO NOT ignore the warnings!!!!

Code:

mingw32-g++.exe -Wall -fexceptions -g -Wmissing-include-dirs -Wfatal-errors -Wno-unused-local-typedefs  -c E:\OpenSourceCode\Test\testcpp\main.cpp -o obj\Debug\main.o
E:\OpenSourceCode\Test\testcpp\main.cpp:87:33: warning: multi-character character constant [-Wmultichar]
     for (int i = 1; *wordptr != 'EOF'; i++) //select the correct table
                                 ^
E:\OpenSourceCode\Test\testcpp\main.cpp:113:21: warning: multi-character character constant [-Wmultichar]
     if (*wordptr == 'EOF')
                     ^
E:\OpenSourceCode\Test\testcpp\main.cpp: In function 'float ceiling(float, float)':
E:\OpenSourceCode\Test\testcpp\main.cpp:23:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
E:\OpenSourceCode\Test\testcpp\main.cpp: In function 'int locomotives_required(double, double, double)':
E:\OpenSourceCode\Test\testcpp\main.cpp:115:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

*wordptr != 'EOF'
should be
wordptr != nullptr
or just
wordptr

strtok (which you shouldn't use, btw) returns a nullptr when no more matches are found.
You should use streams or string's find functions instead of strtok. You are leaking memory and potentially wandering into undefined land.
Also fix the warnings, as pointed out already.

You may want to start by increasing your compiler warning level and fixing all the warnings being generated by your code:

main.cpp|87|warning: multi-character character constant [-Wmultichar]|
main.cpp|113|warning: multi-character character constant [-Wmultichar]|
main.cpp||In function ‘float ceiling(float, float)’:|
main.cpp|15|warning: no previous declaration for ‘float ceiling(float, float)’ [-Wmissing-declarations]|
main.cpp|19|warning: comparing floating point with == or != is unsafe [-Wfloat-equal]|
main.cpp|21|warning: comparing floating point with == or != is unsafe [-Wfloat-equal]|
main.cpp||In function ‘char* tokenizer(std::string)’:|
main.cpp|25|warning: no previous declaration for ‘char* tokenizer(std::string)’ [-Wmissing-declarations]|
main.cpp||In function ‘double slot_capacity_required(double, double, double, double)’:|
main.cpp|48|warning: no previous declaration for ‘double slot_capacity_required(double, double, double, double)’ [-Wmissing-declarations]|
main.cpp||In function ‘double wagons_required(double, double, double)’:|
main.cpp|53|warning: no previous declaration for ‘double wagons_required(double, double, double)’ [-Wmissing-declarations]|
main.cpp||In function ‘double tons_per_axle(double)’:|
main.cpp|58|warning: no previous declaration for ‘double tons_per_axle(double)’ [-Wmissing-declarations]|
main.cpp||In function ‘double train_tons_to(double, double, double)’:|
main.cpp|63|warning: no previous declaration for ‘double train_tons_to(double, double, double)’ [-Wmissing-declarations]|
main.cpp||In function ‘double train_tons_from(double, double)’:|
main.cpp|68|warning: no previous declaration for ‘double train_tons_from(double, double)’ [-Wmissing-declarations]|
main.cpp||In function ‘int locomotives_required(double, double, double)’:|
main.cpp|74|warning: no previous declaration for ‘int locomotives_required(double, double, double)’ [-Wmissing-declarations]|
main.cpp|87|warning: comparison is always true due to limited range of data type [-Wtype-limits]|
main.cpp|94|warning: comparing floating point with == or != is unsafe [-Wfloat-equal]|
main.cpp|113|warning: comparison is always false due to limited range of data type [-Wtype-limits]|
main.cpp||In function ‘float ceiling(float, float)’:|
main.cpp|23|warning: control reaches end of non-void function [-Wreturn-type]|
main.cpp||In function ‘int locomotives_required(double, double, double)’:|
main.cpp|115|warning: control reaches end of non-void function [-Wreturn-type]|
||=== Build finished: 0 errors, 17 warnings (0 minutes, 1 seconds) ===|

With all due respect, are my funny results coming from these warnings or are they just a side note?

Yes, it is most likely one of these warnings that are causing your problems.

Jim

They are more than likely part of your problems.
Comparing against 'EOF' is wrong and will never give you sensible results unless you're very lucky.
Your functions not returning something can result in undefined behaviour, returning garbage to you, or crashing if you're unlucky.

Originally Posted by jimblumberg

Yes, I use Code::Blocks, with g++ 4.8.1, and my warning messages are as posted.

Jim

Im using it on windows and I go to compiler settings and Im trying to switch on enable warnings.

I strongly suggest that you use braces even when they are unnecessary because the body of the if statement (etc) consists of a single statement: you still have not fixed the logic error that I pointed out related to the indentation problem that I noted.