I have a file which contains a year and the name of an associated file to be read. I need to extract the data in the txt file and perform some calculations.
（ year data file）
2004 2004data.txt
2005 2005data.txt
2006 2006data.txt
Here is what I do. I first declare "char yeardata" and then pass "2004data.txt" to it. Then I call yeardata in ifstream to extract the data inside the file "2004data.txt". The problem is that char yeardata is not constant so I cannot pass the file to it. It doesn't work if I change "char yeardata" to "const char yeardata".
Code:
int oldnewcomp_temp(char* lcfile) {
using namespace std;
I want to use a const char* as a buffer. I am reading values from a file and adding them to a buffer. How to extract the values is simple enough. I am reading through a filestream, reading each character into a char pointer and progressing that char pointer every time. I have another char pointer marking the start positon
eg.
char *mychar = new char; char *char1 = new char; char *char2 = new char; const char *constchar ; char2 = char1; while(filestream.read(mychar,1) { *char1 = *mychar; ++char1; }
Then I get this problem: constchar = mychar; // const char* = char*.
Constchar does not catch all the data in other words. At some stage some data is lost due to zeros in the data.. How can I put values into a const char and get around this problem? The const char* will //only record everything up until the first zero.
I'm currently finishing up an assignment that was half written by my professor. Below in the testGrades section of code there are two errors both are the same message.
Error: no matching function for call to Grades:: Grades(const char [15])
Test Grades
//Purpose: Test program for the class Grades // Create stu1 Grades object // Add 5 grades to stu1 - only 3 can be stored in stu1 - other 2 discarded // Create stu2 Grades object // Add only 2 grades
I have data that is coming into my buffer via popen (process data, not a file). Every seven records is a new set [0-6]. I am trying to 'print out the array line/element value' and 'change the value of element [2] to 0', but my loop appears to be looping through every character and not just every line?
What is the programmers responsibility with respect to const char * returned by various functions, like the C++ string class c_str() function which returns a const char * to an c style string array? In VC++ I cannot delete a const char * which holds a string literal. Take the following code for example:
Code: void func() //a useless function with illustrative code { string s1("abcd"); string s2("efgh"); const char * cc1 = s1.c_str(); //c_str() returns a const char * c style string pointer s2.c_str(); //this returns a const char *, which must be allocated on the heap right? delete cc1; //produces run time error in Release mode in VC++ }
The problem with the above code snip is that space is allocated on the heap (or so I believe) for the const char *'s returned by the 2 calls to c_str(). The delete attempt fails and there is no opportunity to delete the space allocated by const char * because its not assigned to anything (however I see c_str() used this way extensively)
So, if I cannot delete a const char *, how does the memory get recovered? Perhaps the string objects s1 and s2 themselves have pointers to the items on the heap made by c_str() calls and they get deleted by the destructors of s1 and s2 when the function ends?
I have data that is coming into my buffer via popen (process data, not a file). Every seven records is a new set [0-6]. I am trying to 'print out the array line/element value' and 'change the value of element [2] to 0', but my loop appears to be looping through every character and not just every line?
199729173 2014-11-16 10:09:34 Found String! 198397652 2014-11-14 15:10:10 Found String! 198397685 2014-11-14 15:10:13 Found String! 198398295 2014-11-14 15:11:14 Found String!
I have a class that defines a window (a popup dialog of sorts), and I want the name of that window to be constant. The only problem is that the name of the popup needs to match the title of the parent window, and I get the name of the parent in the constructor. So how do I go about defining this member variable to be constant and initializing it with a value in the constructor?
I want to do something like this, but I know this isn't allowed:
/* class.h */ class foo { public: foo(*parentWindowPtr);
[Code] .....
I should mention that yes the name of the parent window is const char *, and I would like to keep it this way.
I am a newbie to C++ and VS ++. I have created a windows form application by dragging and dropping button, label..etc. i wish label text to be appeared as return value from a function. The function returns ' const char* '.how this returned string pointer can be used to display label text.?
if we have int x = 5; and we want to convert x which is == 5 to char so for example char number = x doesnot work i understand why , but how to convert it ?
I am trying to convert a char to a CString, I have tried to use the CString.Format method but didn't work. I have a char(char holder[10]) and I want to see if holder is a certain string, say for instance SeaLevel. Below is the code that I also tried.
This sends the buffer to a LIN modem. My question is: can this be done better. If I have a astring of hex numbers like "09 98 88 55 42 FF 00 00 FF BD 89". How could I send this without manually makng a char with hex numbers?
when I was looking for a way how to convert char into numeric value for std::cout I found some old discussion with this statement: Operations on unsigned int are typically faster than on unsigned char, because your processor cannot fetch single bytes but has to get at least a multiple of 4 and mask out the other 3 bytes. Is this true? By using smaller (in bytes) variable I actually slow down my program? I always thought that it is a good practice if I use the smallest variable which will do the work. Is it also dependent on a compiler and OS?
I want to avoid converting the char[] into a string as an intermediate step, since I'm trying to write some "string" parser helpers which don't allocate a bunch of different strings onto the heap. (whole point of this little project is to reduce GC pressure in applications that do alot of string parsing).
basically if I have a char[] that contains {'1','2','3'}, I'd want to to be converted into 123.
I tried messing around with the stackalloc operator in C#, but its illegal to stackalloc a string unfortunately. I also googled around for converting a char[] into a numeric value, but all the solutions convert each individual char into their ASCII code, or convert the char[] into a string as an intermediate step.
How to convert char array into double?,i.e. store char array values into a single double variable. Below is the code that i'm working. Im extracting the value "2255.1682" from char array gpsdata1. I used while loop, extracted the value and stored in "myChar", but i want to store it in double variable "lat1".
