C++ :: Call Only Those Functions Whose Names Are Written In Disk File
May 26, 2013
Here is a working C++ program and its output that reads the names of a certain number of functions whose names are written in a disk file that provides the control parameters in a near-real time fashion. Based on this information, the program calls those functions whose names were given in this text file as parameters. The method I have used is to build a map of functions that connects the names of the functions to the actual functions. Once this map is created, then it is very easy to iterate in such a way that only those selected functions are called.
So far this is working well, and it makes the logic of the code easier because ultimately there will be a large inventory of functions (probably hundreds of functions), and this way of pre-building a map of functions avoids writing hundreds of if statements in the code. Of course, pre-building this reusable map in the background is still equivalent to writing that many if statements, but at least it makes the code very compact and much more automatic, since it is done only once.
But I now have a related question: In this case (when the selected subset of functions to call is given as incoming data as in this example), does C++ make it possible to avoid using maps of functions, by directly applying the string variable that holds the name of the function in order to call the original function immediately For instance, if a string variable s = "MyFunction", then is there a more direct way of using this string as if it were the actual function whose name is spelled exactly in that way? This would make the code even more compact.
Here is the sample test code for the map of functions, and its output:
First of all here is the text file "FileForNamesOfFunctions.TXT" that contains the part of the "data", which is the set of functions select from from the inventory and only call these:
Code:
function2
function3
function5 And here is the C++ code that uses this "data":
I created class called students which suppose to store students names of any sizes in an arrey but when I call the display function it does not show the names.
#include <iostream> #include <sstream> using namespace std; const int SIZE=5; class students{ public: string names[SIZE];
When we are using RAM DISK - the files are stored on the RAM. From what I understand (and saw many examples) in order to read data from file (the file which locate on the RAM) - I need to use the read function.
Is there a chance to get char* (or any pointer) to the content of the file without using the read function ?
If the file locate on the RAM, it seem that it is like I have a buffer on the RAM (like an array which was dynamic allocated) and in the case of a buffer on the ram -> we can use pointers to the data without reading all the data.
example:
class CDATA { int nValue1; int nValue2; double dValue3; double dValue4; char achBuf[10];
I made a text file. I can do all File I/O functions in c. no problem! except that "I want to get the memory address of the beginning of that File", so that I can access each character of the file by incrementing memory address.
i cant display the data written to this file in a switch statement (case 2) what am i doing wrong..the file data is being written into the text file but i cant display it
I'm writing a program that writes to a report in a text file. It uses a struct but with no array. How can I write this so that the report comes out as it should because as of now after i removed the brackets from record which is the variable of the struct my report isn't printing right.
I created class called students which suppose to store students names of in array but when I call the display function it display only the first name. but I want it to display names depending on the array size.
#include <iostream> #include <sstream> using namespace std; const int SIZE=5;
This week we are learning to use templates, and I don't understand how to call my member functions with my template based class. I tried the standard convention of calling member functions, but I keep getting an error saying name following"::" must be a class or namespace name. I'm thinking my problem lies with my typename T, but I am unsure. Line 16 is where I am getting tripped up.
#include "stdafx.h" #include <iostream> #include <string> using namespace std; template<class T> T Set { public:
I want this programming to call functions choose between a customer type and call the relevent function to calculate the final price but it is not calling the functions.
I have almost a hundred names in a text file that I want to convert to email addresses and save to another file. I seem to have it working, but it doesn't print the full names in the email prefix. The output I'm looking for is Doe_John@livebrandm, but I'm only getting D_J@livebrandm. I'm not sure what I should specifically be reading up on that applies to this directly.
i have a vector of stores. i would like to delete the specified choice(store) from the list. Here is what i have but my erase statement is wrong and wont compile.
void Store::deleteSpecifiedStoreFromList(string choice) { for (int i = 0; i < this->stores.size(); i++) { if(this->stores[i].getStoreNames() == choice) { this->stores.erase( std::remove_if( this->stores.begin(), this->stores.end(), choice ), this->stores.end() ); } } }
I am trying to create an array of file names such that when I want to open one of the files, who's name is given in the array, I can call that element of the array. My code for making the array is the following,
Code: char file_name[40]; char *file_locations[N]; // array of N names (*) for(ii=0; ii<=N-1; ii++){ // printing the names of all the files P1_8mag_1.txt - P1_8mag_N.txt sprintf(file_name, "P1_8mag_%i.txt", ii+1);
[Code]....
The problem with this is that in the first step: all elements of the array "file_locations" are the name of the last file in the loop (in this case "P1_8mag_N.txt")What is wrong with this?
I have .db3 file, and he has 14 tables,and every table has certain number of columns. Example i have table called "BASIC_INFO" and that table has columns "First Name", "Last Name" and "Age".
How can i get name of table and name of every column,so if i some day add column "Male" i get name of this column too. I need first to calculate number of columns,put that in some integer, and then for example create string array which will contain : array[0] = "First Name" ,array[1] = "Last Name"...
SQLiteConnection myConn = new SQLiteConnection("Data Source=" + DB3Path + ";Version=3;New=False;Compress=True;"); //string query = "Select * From " + DB3Path + ".INFORMATION_SCHEMA.COLUMNS"; string query = "Select * From BASIC_INFO.INFORMATION_SCHEMA.COLUMNS;"; SQLiteCommand sqCommand = new SQLiteCommand(query);
[Code] ....
I tried this too:
string query = "select * from INFORMATION_SCHEMA.COLUMNS" + "where TABLE_Name='BASIC_INFO'" + "order by ORDINAL_POSITION;"; string query = "SELECT TOP 0 * FROM BASIC_INFO";
I am having trouble reading in a file of 10 names into an array. Ive already allocated the memory, I just keep getting a seg fault when I try and read in the names.
I'm trying to arrange names alphabetically from a text file. Inside my textfile, it's like : "John", "Edward", "Peaches", "Anna"... etc.(It has thousand more names, all with quotations, separated by comma and I think it's not typed line by line... but using only one line). How can I read each name separately?
this code, it works if the text file contains names separated by lines and without commas and quotations. I do not know with the case I've stated above.
string numbers[1000]; string line; string number; string y; string x; int z = 1; ifstream myfile; myfile.open("names.txt");
[Code]...
This only shows the data inside text file. I'm new in c++.
A teacher has asked all her students to line up single file according to their first name. For example, in one class Amy will be in front of the line and Yolanda will be at the end.
Write a program that will read in a file of names. Names should be read until there are no more names to be read. Use LineUp.txt as a test file for your program.
Once all the names have been read in display which student will be at the front of the line and which one would be at the end of the line. You may assume that no two students have the same name.
These are the name in the LineUp.txt file if needed: Cooper Gavin Joseph Sierra Kacie Dylan Kaylee Will
How can I take in a path name like "C:myfolderfile.txt" where the user enters exactly that? I've tried putting the arg into a string, then looping through the string to find the '\', but by that time it is too late as c++ considers the '' as a escape character.
Is this even possible? I've googled it and everyone just says to make the user input the path with double \ or with a /.
Any algorithm or function to rotate a displayed circle. To turn it 360 degrees like a car-tire. (It's needed to turn a turn-table in a model-railrod control program) .....
I'm trying to write a program that writes data to a disk in C++ without caring about it's file system. Here is what I can do so far:
#include <iostream> #include <unistd.h> #include <fcntl.h> using namespace std; char buffer[] = "Wow! I'm writing this data to a disk without puttting it into a file!"; int main(){ int Disk=open("/dev/sdb",O_RDWR); write(Disk,buffer,sizeof(buffer)); close(Disk); return 0;}
But this program can only write ASCII characters to the disk. But what if I want to mainipulate bits on the disk, how would I do that?
I just recently started looking into C++ programming so I don't know much.
I was wondering is it possible to write a program to pick a random name from a list of names, which are in a .txt file? or if I could ask the user to input the list of names and then let the program pick a random name?
