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Join Date: May 2008
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Newbie Poster
Hi,
I'm very new to C++ and was wondering how I would go about searching for a string (AT+COPS?) in a file and displaying everything to the right of the string, could someone point me in the direction of a guide
cheers
I'm very new to C++ and was wondering how I would go about searching for a string (AT+COPS?) in a file and displaying everything to the right of the string, could someone point me in the direction of a guide
cheers
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Join Date: May 2006
Location: ★ ijug.net ★
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Posting Shark
Open the file read it line by line as a string and then use a string api to search for the keyword. It is quite cumbersome homework I would say.
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Join Date: May 2008
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Posting Whiz
The hardest part is opening the file, then it's just like reading input from cin:
#include <fstream>
#include <iostream>
#include <string>
int main()
{
std::ifstream is("myfile");
std::string line;
while (std::getline(is, line)) {
std::string::size_type start = line.find("AT+COPS");
if (start != std::string::npos)
std::cout << line.substr(start) << '\n';
}
} If at first you don't succeed, keep on sucking until you do succeed.
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Newbie Poster
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Originally Posted by Radical Edward 
The hardest part is opening the file, then it's just like reading input from cin:
#include <fstream> #include <iostream> #include <string> int main() { std::ifstream is("myfile"); std::string line; while (std::getline(is, line)) { std::string::size_type start = line.find("AT+COPS"); if (start != std::string::npos) std::cout << line.substr(start) << '\n'; } }
to assignt the output to a varaible would I do something like
String copsoutput;
copsoutput = line.substr(start);
I'm more of a visual baic & c# man, and wish my project would let write it in VB or C#
cheers
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Join Date: Aug 2005
Location: near St Louis, Missouri, USA
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>> I'm more of a visual baic & c# man, and wish my project would let write it in VB or C#
This is c++ board. If you want vb or c# then ask your question there.
>>String copsoutput;
That needs to be lower-case s on string
>>to assignt the output to a varaible would I do something like
Yes -- you got the idea
This is c++ board. If you want vb or c# then ask your question there.
>>String copsoutput;
That needs to be lower-case s on string
string copsoutput;
>>to assignt the output to a varaible would I do something like
Yes -- you got the idea
Last edited by Ancient Dragon : May 19th, 2008 at 12:08 pm.
I think it's about time we voted for senators with breasts. After all, we've been voting for boobs long enough. ~Clarie Sargent, Arizona senatorial candidate
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
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Newbie Poster
lucky I'm trying to write a c++ program then 
anyhow when i try to complie the app using
I receive the following error:
cannot convert std::string to const void for argument 2 to ssize_t write(int, const void*, size_t)
anyhow when i try to complie the app using
while (std::getline(is, line))
{
std::string::size_type start = line.find("+COPS:");
if (start != std::string::npos)
write(lcd,secondrow,sizeof(secondrow));
copsoutput = line.substr(start);
write(lcd,copsoutput,sizeof(copsoutput));
}I receive the following error:
cannot convert std::string to const void for argument 2 to ssize_t write(int, const void*, size_t)
Last edited by uk101man : May 19th, 2008 at 12:28 pm.
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>>cannot convert std::string to const void for argument 2 to ssize_t write(int, const void*, size_t)
the function write is wanting a pointer as the second parameter and you are passing std::string. The third parameter is also wrong. try this:
the function write is wanting a pointer as the second parameter and you are passing std::string. The third parameter is also wrong. try this:
write(lcd,copsoutput.c_str(), copsoutput.length()); Last edited by Ancient Dragon : May 19th, 2008 at 12:37 pm.
I think it's about time we voted for senators with breasts. After all, we've been voting for boobs long enough. ~Clarie Sargent, Arizona senatorial candidate
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
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Newbie Poster
now the app compiles but when I run it I thrown out with
terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::substr Aborted
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Join Date: Aug 2005
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what is secondrow ?
while (std::getline(is, line))
{
std::string::size_type start = line.find("+COPS:");
if (start != std::string::npos)
{
write(lcd,secondrow,sizeof(secondrow));
copsoutput = line.substr(start);
write(lcd,copsoutput.c_str(), copsoutput.length());
}
} Last edited by Ancient Dragon : May 19th, 2008 at 1:12 pm.
I think it's about time we voted for senators with breasts. After all, we've been voting for boobs long enough. ~Clarie Sargent, Arizona senatorial candidate
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
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