I wish there was an option in the "What are you posting" for tutorials hehe. But I guess I will just have to right it here :). If anyone else has any pointers (pun intended) let me know ;).
Ok if your like me and were wondering how to accept command line arguements I am going to show you how (I couldn't find any detailed enough to explain to me anyways).
If you have ever seen some code where int main has a some parameters but weren't sure what they were?
int main(int argc, char *argv[]){
}well here it is broken down
/*int argc is the number of arguements that your program will take
and char * argv[] is a (correct me if I'm wrong experts) pointer char array (an array of pointers?) and it stores what arguements are passed to the program.
IMPORTANT: always assume argv[0] is the program name otherwise your program won't work.Now i will show you a few examples
Example one:
#include <iostream>
#include <fstream>
using namespace std;
int main(int argc, char * argv[0])
{
if(argc!=2){
cout<<argv[0]<<" string"<<endl;
}
else{
cout<<argv[1];
}
}ok so lets break it down :P
if(argc!=2){
cout<<argv[0]<<" string"<<endl;
}that says if there isn't an arguement then print program's name and string
SUPER NOTE: remember that the last spot in any array is reserved
next:
else{
cout<<argv[1];
}basically if there is an arguement print it out
and last example is the code that i wrote with my current knowledge of c++ and ive commented it so as too keep this sort of short
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main(int argc,char * argv[]){
string input; //someplace to store our input :)
int x,y,x1,x2; //x and y are for the loop and the main if check and x1 and x2 are for addition.
if(argc!=2){ // if there are no arguements cout usage
cout<<"Usage: "<<argv[0]<<" name"<<endl; // argv[0] is the programs name even if you rename it.
}
else{
ofstream file (argv[1]); //the 1st arguement is our output files name
//NOTE: that you can put anything where file is but you have to change all subsequent calls to it.
loop: // our goto loop , you'll see later.
if(y!=1){ // Main if check
cout<<"Hello World!,\nWelcome to Test "<<argv[1]<<endl;
cout<<"Commands: add[2] "<<endl;
cout<<"Enter a Command: ";
cin>>input;
for(x=0; x<1;){ // Main loop
if(input=="add[2]"){ //if user typed add[2] then etc...
cout<<"Enter a Number for X1: ";
file<<"Enter a Number for X1: ";
cin>>x1;
file<<x1; //VERY important the file part says to output the value of x1 to the file (in my case test.txt)
cout<<"\nEnter a Number for X2: ";
file<<"\nEnter a Number for X2: ";
cin>>x2;
file<<x2;
cout<<"\nAnswer: "<<x1+x2<<endl;
file<<"\nAnswer: "<<x1+x2<<endl;
cout<<"Press Enter to Continue..."<<endl;
cin.get();
goto loop; // goto loop. repeat as long as input is not exit. if input isnt either one the print add[2]
}
else if(input=="exit")
{
y=1;
cout<<"exiting..";
goto loop;
}
else {
cout<<"Enter add[2]";
goto loop; // input check
}
}
}
}
}
// and we are done :)Hope this helps some people out it took me awhile to figure this out :)
Note for Admins and moderator: I noticed that we only have one tutorial it would be great if we had more which is why i would like to recommend adding a tutorial spot in the drop bar of What are you posting :)
