i found a lot about how to convert int to const char * but non of them explain correctly or sometimes dont even work.
Here is my code:
#include <stdio.h>
#include <cstdlib>
using namespace std;
int main () {
int i =0;
char c1 =0;
char c2 =0;
[code]....
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;
int year;
char yeardata;
[Code] ....
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.
Now I am stuck with getting const char* array from function to main.
Code:
const char* values[3];
strings_to_array()
printf("%s
", values[1]);
printf("%s
", values[2]); function: Code:
const char* strings_to_array()
}
[code]....
First, I cant get strings printed out in main.
Second, is here way to get number of such elements which array contains like higher languages have "count" or "ubound" or such?
Third, next function which need that array assumes that array of const chars* is 1 based. Can that be set in C or here are allways zero based arrays?
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
#include <iostream>
#include <string>
#include <iomanip>
#include "Grades.h"
using namespace std;
[Code] .....
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?
code:
char* Data(){
char buff[BUFSIZ];
FILE *fp = popen("php order.php 155", "r");
std::string::size_type sz;
while(fgets(buff, sizeof buff, fp) != NULL)
}
[code]....
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?
Code:
char* Data(){
char buff[BUFSIZ];
FILE *fp = popen("php order.php 155", "r");
std::string::size_type sz;
while(fgets(buff, sizeof buff, fp) != NULL) {
const char * cstr2 = buff;
for(int i = 0; i < 6; ++i){
[code]...
expected output:
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!
raw inbound data [URL]
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.?
View 9 Replies View RelatedAre there other ways of calling a const/non-const override? I want to defined some functions in terms of others, particularly accessors which might or might not require constness- in order to not copy & paste code. This is my current solution:
struct dumbArray {
dumbArray(unsigned int size):
m_array(new int[size]){
}
~dumbArray(){
delete m_array;
[Code] .....
difference between const and static const, more effectively. I know the basic concept of const and static but I need clear explanation of declaring "const" and "static const"
Ex:
const int a;
static const int a;
Is there any way to cast a non-const variable to const one?
I want to read variable n from file and then use it to declare array "int arr[n]", but because n is non-const, the compiler doesn't allow me to do that.
I am writing a basic keylogger and i want to add data to log file, but it says that i cant convert char to int. Everything else works fine.
Code:
#include <iostream>#include <windows.h>
#include <stdio.h>
#include <time.h>
using namespace std;
[Code] ....
Example
char A[4]
gets(A) --> 1234
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 ?
View 14 Replies View RelatedIs there anyway to convert std::string to char*?
Like:
std::string x="hello world";
char* y=x;
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.
if(holder == "SeaLevel")
{
//do something
}
I have this code working:
char tmp_wku[3];
tmp_wku[0]=0x01;
tmp_wku[1]=0x9D;
tmp_wku[2]=0x62;
char tmp_com[11];
[Code] ....
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?
View 2 Replies View RelatedI am trying to convert char to time and I found the following code. But it gives me a -1 on "converted" instead of time.
#include <stdio.h>
#include <time.h>
#include <iostream>
using namespace std;
[Code].....
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.
I am trying to compile the following C code in C++ with visual studio 2010:
Code:
#include <windows.h>
#include <stdio.h>
void test(FARPROC addr) {
__try {
addr();
printf("ok
[Code] ....
But I get the compilation error: main.cpp(25): error C2440: 'type cast' : cannot convert from 'char [4096]' to 'FARPROC'
How would I make this compile in C++?
I want to convert int to char array for get the total of digits like this..
Code:
int total;
char charnum[2] = (char)total; //this is the problem
int num = 0;
for (int i = 0; i <2; i++)
{ num += charNum[i] -48;}
cout << num;
If total was 42 i want to get output as 6. for this purpose i want to convert int to char.
Currently I have:
Code:
char my_array[4] = { '1', '2', '3', '4' };
how do I convert the above to a string of: "1234"
.I have this string that I need to convert into a 2d char array like this:
String str= "A,E,B,I,M,Y#N,R,C,A,T,S";
I know how to use delimiter and split string and I know how to convert but only from string to char[].I need something like this:
Input: String str= "A,E,B,I,M,Y#N,R,C,A,T,S";
Output: [A] [E] [B] [I] [M] [Y][N] [R] [C] [A] [T] [S]