break a string up c++

The easiest way: Use a 'stringstream', e.g.

#include <sstream>

string line = "120 520 36 4 55 -1"
string strNum;

stringstream ss;
int i = 0;

ss << line;

while(!ss.eof()) {

ss >> strNum;

cout << i << " -> " << strNum << endl;

++i;
}

You could even use an 'int num;', e.g.

#include <sstream>

string line = "120 520 36 4 55 -1"
int num;

stringstream ss;
int i = 0;

ss << line;

while(!ss.eof()) {

ss >> num;

cout << i << " -> " << num << endl;

++i;
}

Is there a way to do this without the use of sstream, I cant use it in my current project?

Sure, there are plenty of ways to do that, with 'strtok()' proabaly being the most common one:

#include <string.h>

string line = "120 520 36 4 55 -1"
string strNum;

char seps[]   = " ";
char *token;
char* tmp = strdup(line.c_str());

   /* Establish string and get the first token: */
   token = strtok( tmp, seps );
   while( token != NULL )
   {
      /* While there are tokens in "tmp" */
      strNum = = token;
      cout << strNum << endl;
      /* Get next token: */
      token = strtok( NULL, seps );
   }

free(tmp);

if you know how many numbers you are expecting you may use, sscanf:
            
char* line = "120 520 36 4 55 -1"
int N[6],i;
sscanf(line,"%i %i %i %i %i %i",N[0],N[1],N[2],N[3],N[4],N[5]);
for (i=0;i<6;i++){
count << N[i];
}
cout << endl;

Another way is to do like this

void split(const std::string& str,
               std::vector<std::string>& tokens,
               const std::string& delimiters = " ")
{
    std::string::size_type lastPos = str.find_first_not_of(delimiters, 0);
    std::string::size_type pos = str.find_first_of(delimiters, lastPos);
      
    while (std::string::npos != pos || std::string::npos != lastPos)
    {
        tokens.push_back(str.substr(lastPos, pos - lastPos));
        lastPos = str.find_first_not_of(delimiters, pos);
        pos = str.find_first_of(delimiters, lastPos);
    }
}

...
std::string line = "120 520 36 4 55 -1";
std::vector<std::string> result;
split(line, result);

Thanks that helped alot.