c

[Guest_imported]

atoi how does it work

 

[rwb1959]

Are you asking how to use it???
If so, the "man" page...

NAME
atoi - convert a string to an integer.

SYNOPSIS
#include <stdlib.h>

int atoi(const char *nptr);

DESCRIPTION
The atoi() function converts the initial portion of the
string pointed to by nptr to int. The behaviour is the
same as

strtol(nptr, (char **)NULL, 10);

except that atoi() does not detect errors.

RETURN VALUE
The converted value.

...if you are asking how it works internally, you can look at...

http://www.sv.vt.edu/classes/ESM4714/data_sets/kriz/a/atoi.c.html

...or the GNU source...
int atoi(const char *number)
{
register int n = 0, neg = 0;

while (*number <= ' ' && *number > 0)
++number;
if (*number == '-')
{
neg = 1;
++number;
}
else if (*number == '+')
++number;
while (*number>='0' && *number<='9')
n = (n * 10) + ((*number++) - '0');
return (neg ? -n : n);
}

 

[trmurali]

i have doubt in C language of header file time.h

in that we have clock() function it reterns processor clock speed,

i need to find the total time to execute the function

then how can i find it?

 

[rwb1959]

A very common tool used for finding out
how much time a program spends in a funtion
are &quot;prof&quot; and &quot;gprof&quot;. This URL will give you a wealth of information
on various tools including &quot;prof&quot;...

http://www.ait.iastate.edu/olc/programming/development/homepage.html

You should also look at the man pages for prof and gprof.
Essentially, you compile like...

cc -o prog -p prog.c <-- to use prof
cc -o prog -pg prog.c <-- to use gprof

...then you run the program...

prog

...then you display the profile...

prof prog

...or...

gprof prog