Why does this code not work with the integer 113383?

Question

It's to find out how many operations are needed until the integer is calculated to 1 (Collatz problem).

It works with every integer except 113383. With 113383 the console just doesn't do anyhting, it doesn't print ops, it seems as the program is caught in a loop. Why?

I am using Visual Studio.

#include <iostream>

int main()
{
    int num = 113383;
    int ops = 0;
    while (num != 1) {
        if (num % 2 == 0)
        {
            num /= 2;
            ops++;
        }
        else if (num % 2 == 1)
        {
            num = num * 3 + 1;
            ops++;
        }
    }
    std::cout << ops << std::endl;
    return 0;
}

Answer 1

Because of integer overflow: I've shown intermediate values of num and ops and you see that the values become negative, which is typical for an overflow, as you can see:

New version (with extra output):

#include <iostream>

int main()
{
    int num = 113383;
    int ops = 0;
    while (num != 1) {
        if (num % 2 == 0)
        {
            num /= 2;
            ops++;
            std::cout << "num=" << num << std::endl;
            std::cout << "ops=" << ops << std::endl;
        }
        else if (num % 2 == 1)
        {
            num = num * 3 + 1;
            ops++;
            std::cout << "num=" << num << std::endl;
            std::cout << "ops=" << ops << std::endl;
        }
    }
    std::cout << ops << std::endl;
    return 0;
}

Result:

num=340150
ops=1
num=170075
ops=2
num=510226
ops=3
num=255113
ops=4
num=765340
ops=5
num=382670
ops=6
num=191335
ops=7
num=574006
ops=8
num=287003
ops=9
num=861010
ops=10
num=430505
ops=11
num=1291516
ops=12
num=645758
ops=13
num=322879
ops=14
num=968638
ops=15
num=484319
ops=16
num=1452958
ops=17
num=726479
ops=18
num=2179438
ops=19
num=1089719
ops=20
num=3269158
ops=21
num=1634579
ops=22
num=4903738
ops=23
num=2451869
ops=24
num=7355608
ops=25
num=3677804
ops=26
num=1838902
ops=27
num=919451
ops=28
num=2758354
ops=29
num=1379177
ops=30
num=4137532
ops=31
num=2068766
ops=32
num=1034383
ops=33
num=3103150
ops=34
num=1551575
ops=35
num=4654726
ops=36
num=2327363
ops=37
num=6982090
ops=38
num=3491045
ops=39
num=10473136
ops=40
num=5236568
ops=41
num=2618284
ops=42
num=1309142
ops=43
num=654571
ops=44
num=1963714
ops=45
num=981857
ops=46
num=2945572
ops=47
num=1472786
ops=48
num=736393
ops=49
num=2209180
ops=50
num=1104590
ops=51
num=552295
ops=52
num=1656886
ops=53
num=828443
ops=54
num=2485330
ops=55
num=1242665
ops=56
num=3727996
ops=57
num=1863998
ops=58
num=931999
ops=59
num=2795998
ops=60
num=1397999
ops=61
num=4193998
ops=62
num=2096999
ops=63
num=6290998
ops=64
num=3145499
ops=65
num=9436498
ops=66
num=4718249
ops=67
num=14154748
ops=68
num=7077374
ops=69
num=3538687
ops=70
num=10616062
ops=71
num=5308031
ops=72
num=15924094
ops=73
num=7962047
ops=74
num=23886142
ops=75
num=11943071
ops=76
num=35829214
ops=77
num=17914607
ops=78
num=53743822
ops=79
num=26871911
ops=80
num=80615734
ops=81
num=40307867
ops=82
num=120923602
ops=83
num=60461801
ops=84
num=181385404
ops=85
num=90692702
ops=86
num=45346351
ops=87
num=136039054
ops=88
num=68019527
ops=89
num=204058582
ops=90
num=102029291
ops=91
num=306087874
ops=92
num=153043937
ops=93
num=459131812
ops=94
num=229565906
ops=95
num=114782953
ops=96
num=344348860
ops=97
num=172174430
ops=98
num=86087215
ops=99
num=258261646
ops=100
num=129130823
ops=101
num=387392470
ops=102
num=193696235
ops=103
num=581088706
ops=104
num=290544353
ops=105
num=871633060
ops=106
num=435816530
ops=107
num=217908265
ops=108
num=653724796
ops=109
num=326862398
ops=110
num=163431199
ops=111
num=490293598
ops=112
num=245146799
ops=113
num=735440398
ops=114
num=367720199
ops=115
num=1103160598
ops=116
num=551580299
ops=117
num=1654740898
ops=118
num=827370449
ops=119
num=-1812855948
ops=120
num=-906427974
ops=121
num=-453213987
ops=122

I would advise you to go for larger integer types, like long, long long, or even larger.