Can anybody help me to understand below code ?

Qt embedded developer

Today i have read one code which extract the latest db version from string "1.5,10,1.3$1.5,11,1.4".
for that i had implemented below code :

#include <iostream>
#include <vector>

#define DBGF_TRACE printf
using namespace std;

int main()
{
    cout<<"Hello World";
    string	strOTAZip;
    
    string strSettingkeyvalue= "1.5,10,1.3$1.5,11,1.4";

   if(strSettingkeyvalue !="" && strSettingkeyvalue !="0" && strSettingkeyvalue.size()>4)
   {
	// 1. concatenate the zip version with OTA link

	std::vector<string> vecGetSplittedZipVersion;
	std::string  delims= ", $" ;
	size_t beg, pos = 0;

	while ((beg = strSettingkeyvalue.find_first_not_of(delims, pos)) != std::string::npos)
       {
	   pos = strSettingkeyvalue.find_first_of(delims, beg + 1);
	   vecGetSplittedZipVersion.push_back(strSettingkeyvalue.substr(beg, pos - beg));
	   std::cout << strSettingkeyvalue.substr(beg, pos - beg) << std::endl;
	}

	string	ZipVerName = vecGetSplittedZipVersion[vecGetSplittedZipVersion.size()-2];

	strOTAZip ="/Config"+ZipVerName+".zip";

   }
	
    std::cout <<strOTAZip;

    return 0;
}

I am getting expected ouput as "/Config11.zip".

But my mind can not understand the part of code mentioned below :

while ((beg = strSettingkeyvalue.find_first_not_of(delims, pos)) != std::string::npos)
{
	pos = strSettingkeyvalue.find_first_of(delims, beg + 1);
	vecGetSplittedZipVersion.push_back(strSettingkeyvalue.substr(beg, pos - beg));
	std::cout << strSettingkeyvalue.substr(beg, pos - beg) << std::endl;
}

string	ZipVerName = vecGetSplittedZipVersion[vecGetSplittedZipVersion.size()-2];
strOTAZip ="/Config"+ZipVerName+".zip";

So please help me to understand above part of code. how it iterate and find the my latest db version from string ?

JonB

@Qt-embedded-developer said in Can anybody help me to understand below code ?:

i want to understand

Then you need to read the docs and analyze the code, I don't know what "explanation" you are expecting!

beg is set to the first non-", $" character. pos is then set to the next ", $" character, starting from just after pos. substr(beg, pos - beg) takes the substring starting at beg and ending at pos - 1. So, just as you would expect, it extracts the next "token" between those delimiter characters. And then because you have it in a while loop it moves on to get the next one, restarting at pos, where it got to last time.

jsulm

@Qt-embedded-developer said in Can anybody help me to understand below code ?:

But my mind can not understand the part of code mentioned below

What exactly is not clear (which exact part)?
Also please format the code properly!

JonB

@Qt-embedded-developer
A glance tells you that it splits the string on delims= ", $", so I would guess on any of comma, space or dollar. Then all you have to do is look at the std::string documentation for find_first_not_of/find_first_of/substr() methods to see what they do (pretty obvious). What is the mystery?

Qt embedded developer

@jsulm I have formatted the code. the unclear part is

while ((beg = strSettingkeyvalue.find_first_not_of(delims, pos)) != std::string::npos)
{
	pos = strSettingkeyvalue.find_first_of(delims, beg + 1);
	vecGetSplittedZipVersion.push_back(strSettingkeyvalue.substr(beg, pos - beg));

i want to understand what exactly this 3 statement is doing in my example i want to understand.

i have seen find_first_not_of() and find_first_of() first time so what exactly this function is doing in my example code ?

JonB

@Qt-embedded-developer said in Can anybody help me to understand below code ?:

i want to understand

Then you need to read the docs and analyze the code, I don't know what "explanation" you are expecting!

beg is set to the first non-", $" character. pos is then set to the next ", $" character, starting from just after pos. substr(beg, pos - beg) takes the substring starting at beg and ending at pos - 1. So, just as you would expect, it extracts the next "token" between those delimiter characters. And then because you have it in a while loop it moves on to get the next one, restarting at pos, where it got to last time.