Getting Integer from String?

[jobo]

Hello,

If I'm given a string that always starts with the word "free" followed
by an integer ("free xx"). How do I parse through the characters and
get to the integer value? Thanks.

 

[Chris McDonald]

If I'm given a string that always starts with the word "free" followed
by an integer ("free xx"). How do I parse through the characters and
get to the integer value? Thanks.

Sounds like homework, but
If char *str = "free 123";
then the address of the '1' will be str+5, or &str[5] .

 

[mark_bluemel]

Hello,

If I'm given a string that always starts with the word "free" followed
by an integer ("free xx"). How do I parse through the characters and
get to the integer value? Thanks.

Is there always a space between "free" and the integer?

Do you know for certain that there will be no characters after the
integer?

If so, then if the string is provided as a char * called (e.g.) "str"
then the integer (as a string) will be at str+5 and you could use one
of the standard functions (from the manual) to convert it to an integer
or long datatype.

There are other approaches, for example there is a function (also in
the manual) for scanning strings and extracting data from them. Or you
could write a routine that searches through the string till it find the
first digit, and then continues, multiplying a running total by 10 (I
presume the integer is in decimal representation) and adding the value
of the next digit, till you run out of digits.

 

[Andrew Poelstra]

Hello,

If I'm given a string that always starts with the word "free" followed
by an integer ("free xx"). How do I parse through the characters and
get to the integer value? Thanks.

scanf("free %d", &n);

Any good C textbook should tell you that.

 

[mark_bluemel]

scanf("free %d", &n);

Actually for a string, he needs sscanf() surely...

 

[Andrew Poelstra]

Actually for a string, he needs sscanf() surely...

I misread being "given" a string as input from stdin. My bad.

 

[Peter Karlsson]

Hello,

If I'm given a string that always starts with the word "free" followed
by an integer ("free xx"). How do I parse through the characters and
get to the integer value? Thanks.

strtol?

//Peter

 

[CBFalconer]

strtol?

There are few things stupider than an erroneous response to a two
months old query.

 

[Xavier Serrand]

long int convert (char * s, char *endptr, int base)
{
return strtol (s+3, &endptr, base);
}