CODEWITHSUNDEEP
cstringchar
Itzik984
Itzik984

Reputation: 16764

C: Get substring before a certain char

For example, I have this string: 10.10.10.10/16

and I want to remove the mask from that IP and get: 10.10.10.10

How could this be done?

Upvotes: 24

Views: 90121

Answers (6)

pmg
pmg

Reputation: 108938

Just put a 0 at the place of the slash

#include <string.h> /* for strchr() */

char address[] = "10.10.10.10/10";
char *p = strchr(address, '/');
if (!p)
{
    /* deal with error: / not present" */
    ;
}
else
{
   *p = 0;
}

I don't know if this works in C++

Upvotes: 19

nav
nav

Reputation: 440

Example in C++

#include <iostream>
using namespace std;

int main() 
{
    std::string addrWithMask("10.0.1.11/10");
    std::size_t pos = addrWithMask.find("/");
    std::string addr = addrWithMask.substr(0,pos);
    std::cout << addr << std::endl;
    return 0;
 }

Upvotes: 1

75inchpianist
75inchpianist

Reputation: 4102

char* pos = strstr(IP,"/"); //IP: the original string
char [16]newIP;
memcpy(newIP,IP,pos-IP);   //not guarenteed to be safe, check value of pos first

Upvotes: 4

Olaf Dietsche
Olaf Dietsche

Reputation: 74028

Example in 

char ipmask[] = "10.10.10.10/16";
char ip[sizeof(ipmask)];
char *slash;
strcpy(ip, ipmask);
slash = strchr(ip, '/');
if (slash != 0)
    *slash = 0;

Upvotes: 0

Roee Gavirel
Roee Gavirel

Reputation: 19445

I see this is in C so I guess your "string" is "char*"?
If so you can have a small function which alternate a string and "cut" it at a specific char:

void cutAtChar(char* str, char c)
{
    //valid parameter
    if (!str) return;

    //find the char you want or the end of the string.
    while (*char != '\0' && *char != c) char++;

    //make that location the end of the string (if it wasn't already).
    *char = '\0';
}

Upvotes: 0

Andy Prowl
Andy Prowl

Reputation: 126432

Here is how you would do it in C++ (the question was tagged as C++ when I answered):

#include <string>
#include <iostream>

std::string process(std::string const& s)
{
    std::string::size_type pos = s.find('/');
    if (pos != std::string::npos)
    {
        return s.substr(0, pos);
    }
    else
    {
        return s;
    }
}

int main(){

    std::string s = process("10.10.10.10/16");
    std::cout << s;
}

Upvotes: 36

Related Questions