CODEWITHSUNDEEP
cstdstrtol
Mark E
Mark E

Reputation: 3483

function strtol in C out of range... or not

I try to read a number from a string with strtol() and it returns the LONG_MAX number which is supposed to return when the number is out of range, but my number is not that big

main(){
    char linea[30]={"110111010111111000000000"};
    long num=strtol(linea,NULL,0);
    printf("%s\n%X",linea,num);
}

Actual Result:
110111010111111000000000
7FFFFFFF

Needed Result:
110111010111111000000000
DD7C00

Upvotes: 2

Views: 1015

Answers (2)

brepro
brepro

Reputation: 143

According to the man page for strtol, the '0' argument you've given means 'use you best judgement', which in this case is decimal. If you want it to convert a binary number, as the 'Needed result' you've specified suggests, don't use '0', use '2'.

Upvotes: 5

Hunter McMillen
Hunter McMillen

Reputation: 61510

probably because you pass in base 0

try:

int main(){
    char linea[30] = {"110111010111111000000000"};
    long num       = strtol(linea, NULL, 10);
    printf("%s\n%X", linea, num);
}

EDIT Apparently base 0 is a special value for the strtol function:

If the value of base is 0, the expected form of the subject sequence is that of a decimal constant, octal constant, or hexadecimal constant, any of which may be preceded by a '+' or '-' sign.

So I guess you can use 0, sorry for doubting you.

Upvotes: 0

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