read parameters from txt in Linux - c++

Question

I need to read parameters from a txt file for my program in Linux. But the result is that some of the parameters read from the txt file have the correct value, but some of them have a wrong value. Somebody has met this problem? I have translated the format of the txt in windows into Linux with the command dos2unix. I need your help, Thanks.
The read function is as follows:
template <class T>int ReadFileVar(ifstream *inClientFile, const char var_name[], T *var)
{
//inClientFile - pointer to the previously opened File stream
//var_name - contains the name of the variable
//var - pointer to a long, the function will return the value of the variable in this
int length_var_name = (int) strlen(var_name);
char line[512];
int i, j;
while (inClientFile->getline(line,512))
{
if (line[0] != '/' && line[1] != '/')
{
i = 0;
while (line[i] != '\0')
{
if (!strncmp(&line[i],var_name,length_var_name))
{
j = i + length_var_name;
while (line[j] != '\0')
{
if ( line[j] >= '0' && line[j] <= '9')
{
*var = (T) atof(&line[j]);
inClientFile->seekg( 0, ios_base::beg ); //back to the beginning of the file
return 0;
}
j++;
}
}
i++;
}
}
}
cerr << var_name << " - cannot be found" << endl;
throw "error reading input data from: ";
return 1; //the specified variable was not found in the file
}
For example:
the parameters in the txt are as follows:,the type of them are long,
nx=100;
ny=100;
nz=100;
ipro=1;
jpro=1;
kpro=1;
but after reading the txt in my program I get these,
nx=100;
ny=100;
nz=15;
ipro=1;
jpro=1;
kpro=100;
I have tested the program under Windows, there it works!

Answer 1

Your code works for me, you must have an error somewhere else or an undefined behavior I didn't spot.
May I suggest a more C++ way to do exactly the same thing :
template <class T>
T ReadFileVar(ifstream& inClientFile, string var_name)
{
string line;
while (getline(inClientFile, line))
{
if (line[0] != '/' && line[1] != '/')
{
size_t pos = line.find(var_name);
if( pos != string::npos) {
pos = line.find('=', pos + 1);
if(pos == string::npos) {
throw std::exception();
}
istringstream iss(line.substr(pos + 1));
T result;
iss >> result;
inClientFile.seekg( 0, ios_base::beg );
return result;
}
}
}
throw std::exception();
}
You could also parse the whole file and store the result in a map instead of searching the whole file for each variable :
map<string, string> ParseFile(ifstream& inClientFile) {
map<string, string> result;
string line;
while (getline(inClientFile, line))
{
if (line[0] != '/' && line[1] != '/')
{
size_t pos = line.find('=');
if(pos == string::npos) {
throw std::exception();
}
string var_name = line.substr(0, pos);
string var_value = line.substr(pos + 1);
result[var_name] = var_value;
}
}
return result;
}
template <class T>
T ReadVar(map<string, string> data, string var_name)
{
map<string, string>::iterator it = data.find(var_name);
if(it == data.end()) {
throw exception();
}
string value = it->second;
istringstream iss(value);
T result;
iss >> result;
return result;
}