This question already has answers here:
printf with std::string?
(9 answers)
Closed 7 months ago.
std::string sszModName = "kernel32.dll";
std::string WinVersion = "WIN81";
std::string MachineGUID= "ce9e95db-5fda-436a-b29a-f5537702c77d";
char buf[1024];
sprintf(buf, "https://nulln.nullnu-ll.nul/nullnulln/api/ireport.php?module=%s&publisher=%s&win=%s&machineguid=%s", sszModName, "ERROR_HASH_VERIFY", WinVersion, MachineGUID);
This code causes program lag, could you help me figure out why?
Try
sprintf(buf,
"https://nulln.nullnu-ll.nul/nullnulln/api/ireport.php?module=%s&publisher=%s&win=%s&machineguid=%s",
sszModName.c_str(),
"ERROR_HASH_VERIFY",
WinVersion.c_str(),
MachineGUID.c_str());
C strings are not the same as C++ strings. spprintf only uses C strings so you must use .c_str() to turn your C++ strings into C strings.
Related
This question already has answers here:
escape R"()" in a raw string in C++
(2 answers)
Include )" in raw string literal without terminating said literal
(3 answers)
Closed 9 months ago.
I want to output a string like this: onclick="func()". So I wrote the following code:
std::string s = R"(
onclick="func()"
)";
But here two )" let the compiler confused.
Please forgive me if it's a silly question.
I googled but found nothing (I don't know which keyword I should use when I googled).
Simply add a unique string outside the ()
std::string s = R"anystring(
onclick="func()"
)anystring";
This question already has answers here:
How to convert a std::string to const char* or char*
(11 answers)
Closed 2 years ago.
I am trying to use the std::rename() function to move a .docx file, however, the name of the file may vary. How can I use a std::string within std::rename() so that it does not have to be a hardcoded filepath, like this std::rename(filepath, destination);?
I don't know how you want to populate the strings in question, but here you go:
std::string fromName {"whatever you're going to do"};
std::string toName {"whatever you're going to do"};
std::rename(fromName.c_str(), toName.c_str());
This question already has answers here:
How to read and write a STL C++ string?
(3 answers)
Closed 4 years ago.
I've recently learnt about std::substr() by searching on Google. I saw a code something like this:
std::string s = "This is an example string";
std::string s1 = s.substr(11, 7);
std::cout << s1 << std::endl;
Now if I try to take input using scanf() function (instead of using std::cin), the program crashes during runtime. Doesn't std::string support using scanf() function?
scanf() belongs to a family of C functions that, being part of the C language rather than C++, offers no direct support for std::string and works instead with null terminated character strings.
If you are using C++, you should generally prefer std::string over null terminated terminated character strings and the input/output library over printf()/scanf() library functions.
This question already has answers here:
How to copy std::string into std::vector<char>? [duplicate]
(2 answers)
Closed 7 years ago.
How to convert a string such as "Hello, world!" into a vector of characters? I've seen many techniques on how to do this for plain arrays, but none for vectors. Here is my code:
string raw_text = "Hello, world!";
vector<char> char_text;
Any way to make a character vector from raw_text?
Thanks in advance!
vector<char> char_text(raw_text.begin(), raw_text.end());
This question already has answers here:
Why do I get a segmentation fault when writing to a "char *s" initialized with a string literal, but not "char s[]"?
(19 answers)
Why can't I write to a string literal while I *can* write to a string object?
(4 answers)
Is it possible to modify a string of char in C?
(9 answers)
Closed 8 years ago.
Basically, I am trying to increment the int value of port. This should be easy but I am a little stuck.
It compile fine, but I got this error when I run it:
Access violation writing location 0x001f5834
#include "stdafx.h"
#include "iostream"
using namespace std;
#define TESTING "5002"
int main()
{
char* port = TESTING;
int portint;
sscanf ( port, "%d", &portint );
portint++;
cout << portint << endl; // it works fine up to here, it prints 5003
sprintf ( port, "%d", portint);
return 0;
}
By default, compiler treats string literals as immutable, and an attempt to modify the contents of one results in an access violation error at run time because these strings are put into code segment, and it's read only. In your case, TESTING is a string literal, you can't not change its values. Try:
char port[] = "5002";
Meanwhile, the compiler should have warning on this: when you assign a const char* type to a char* type.
MS C++ compiler has a compiler option regards this: Zc:strictStrings.
You are trying to write "5003" back into "5002". "5002" is a string literal and cannot be written to.
I'll try to find a good duplicate for this question, because it has been asked in many ways, many times.
In your usage, "5002" becomes a static array of characters and as such can not be modified. I believe K&R address this, but I don't have the book in front of me right now. Behavior would be different if you had declared an array.