All Questions
16,415
questions
3358
votes
83
answers
2.4m
views
How do I iterate over the words of a string?
How do I iterate over the words of a string composed of words separated by whitespace?
Note that I'm not interested in C string functions or that kind of character manipulation/access. I prefer ...
2129
votes
29
answers
4.7m
views
How to convert int to string in C++?
How can I convert from int to the equivalent string in C++? I am aware of two methods. Is there another way?
(1)
int a = 10;
char *intStr = itoa(a);
string str = string(intStr);
(2)
int a = 10;
...
- 24.9k
1082
votes
11
answers
1.2m
views
How to convert a std::string to const char* or char*
How can I convert an std::string to a char* or a const char*?
- 14.1k
1006
votes
31
answers
1.4m
views
How to convert an instance of std::string to lower case
I want to convert a std::string to lowercase. I am aware of the function tolower(). However, in the past I have had issues with this function and it is hardly ideal anyway as using it with a std::...
- 40.3k
902
votes
14
answers
426k
views
std::wstring VS std::string
I am not able to understand the differences between std::string and std::wstring. I know wstring supports wide characters such as Unicode characters. I have got the following questions:
When should I ...
Appu
777
votes
26
answers
2.2m
views
How can I convert a std::string to int?
I want to convert a string to an int and I don't mean ASCII codes.
For a quick run-down, we are passed in an equation as a string. We are to break it down, format it correctly and solve the linear ...
- 7,955
753
votes
16
answers
1.4m
views
Check if a string contains a string in C++
I have a variable of type std::string. I want to check if it contains a certain std::string. How would I do that?
Is there a function that returns true if the string is found, and false if it isn't?...
- 54.7k
728
votes
9
answers
829k
views
Read whole ASCII file into C++ std::string [duplicate]
I need to read a whole file into memory and place it in a C++ std::string.
If I were to read it into a char[], the answer would be very simple:
std::ifstream t;
int length;
t.open("file.txt"); /...
- 41.4k
639
votes
44
answers
1.4m
views
std::string formatting like sprintf
I have to format std::string with sprintf and send it into file stream. How can I do this?
- 63.3k
556
votes
32
answers
368k
views
How to convert an enum to a string in modern C++
Contrary to all other similar questions, this question is about using the new C++ features.
2008 c Is there a simple way to convert C++ enum to string?
2008 c Easy way to use variables of enum types ...
- 52.9k
530
votes
11
answers
495k
views
How can you define a static data member of type const std::string?
I'd like to have a private static constant for a class (in this case a shape-factory).
I'd like to have something of the sort.
class A {
private:
static const string RECTANGLE = "...
- 5,726
488
votes
9
answers
795k
views
Differences between C++ string == and compare()?
I just read some recommendations on using
std::string s = get_string();
std::string t = another_string();
if( !s.compare(t) )
{
instead of
if( s == t )
{
I'm almost always using the last one ...
- 68.4k
478
votes
37
answers
660k
views
How do I tokenize a string in C++?
Java has a convenient split method:
String str = "The quick brown fox";
String[] results = str.split(" ");
Is there an easy way to do this in C++?
- 402k
475
votes
19
answers
1.2m
views
std::string to char*
I want to convert a std::string into a char* or char[] data type.
std::string str = "string";
char* chr = str;
Results in: “error: cannot convert ‘std::string’ to ‘char’ ...”.
What methods are ...
user1598585
457
votes
6
answers
277k
views
How do I print the full value of a long string in gdb?
I want to print the full length of a C-string in GDB. By default it's being abbreviated, how do I force GDB to print the whole string?
- 54.6k
429
votes
23
answers
464k
views
How to get rid of `deprecated conversion from string constant to ‘char*’` warnings in GCC
I'm working on an exceedingly large codebase, and recently upgraded to GCC 4.3, which now triggers this warning:
warning: deprecated conversion from string constant to ‘char*’
Obviously, the correct ...
- 12.9k
420
votes
24
answers
529k
views
How do I check if a C++ std::string starts with a certain string, and convert a substring to an int?
How do I implement the following (Python pseudocode) in C++?
if argv[1].startswith('--foo='):
foo_value = int(argv[1][len('--foo='):])
(For example, if argv[1] is --foo=98, then foo_value is 98.)...
- 147k
387
votes
5
answers
109k
views
How exactly is std::string_view faster than const std::string&?
std::string_view has made it to C++17 and it is widely recommended to use it instead of const std::string&.
One of the reasons is performance.
Can someone explain how exactly std::string_view is/...
- 23.4k
372
votes
30
answers
644k
views
Case-insensitive string comparison in C++ [closed]
What is the best way of doing case-insensitive string comparison in C++ without transforming a string to all uppercase or all lowercase?
Please indicate whether the methods are Unicode-friendly and ...
- 26.3k
365
votes
22
answers
285k
views
Find out if string ends with another string in C++
How can I find out if a string ends with another string in C++?
- 5,517
351
votes
2
answers
241k
views
Why does std::string have a length() member function in addition to size()?
I was reading the answers for How to get the number of characters in a std::string? and found that there is actually a method called length() for std::string (I always used size()).
Is there any ...
- 75.7k
331
votes
23
answers
590k
views
Why can't the switch statement be applied to strings?
Compiling the following code gives the error message: type illegal.
int main()
{
// Compilation error - switch expression of type illegal
switch(std::string("raj"))
{
case&...
- 47.2k
329
votes
31
answers
751k
views
Convert a String In C++ To Upper Case
How could one convert a string to upper case. The examples I have found from googling only have to deal with chars.
- 3,632
304
votes
20
answers
33k
views
What's the rationale for null terminated strings?
As much as I love C and C++, I can't help but scratch my head at the choice of null terminated strings:
Length prefixed (i.e. Pascal) strings existed before C
Length prefixed strings make several ...
- 105k
298
votes
5
answers
1.0m
views
How to convert a char array to a string?
Converting a C++ string to a char array is pretty straightorward using the c_str function of string and then doing strcpy. However, how to do the opposite?
I have a char array like: char arr[ ] = "...
- 11.8k
295
votes
12
answers
509k
views
Remove last character from C++ string
How can I remove last character from a C++ string?
I tried st = substr(st.length()-1); But it didn't work.
- 4,531
284
votes
13
answers
481k
views
Count character occurrences in a string in C++
How can I count the number of "_" in a string like "bla_bla_blabla_bla"?
- 3,244
278
votes
4
answers
275k
views
Why is conversion from string literal to 'char*' valid in C but invalid in C++
The C++11 Standard (ISO/IEC 14882:2011) says in § C.1.1:
char* p = "abc"; // valid in C, invalid in C++
For the C++ it's OK as a pointer to a String Literal is harmful since any attempt to modify it ...
- 7,314
274
votes
19
answers
476k
views
Replace part of a string with another string
How do I replace part of a string with another string using the standard C++ libraries?
QString s("hello $name"); // Example using Qt.
s.replace("$name", "Somename");
- 19.6k
274
votes
19
answers
513k
views
Remove spaces from std::string in C++
What is the preferred way to remove spaces from a string in C++? I could loop through all the characters and build a new string, but is there a better way?
- 11.5k
266
votes
24
answers
151k
views
How do I read an entire file into a std::string in C++?
How do I read a file into a std::string, i.e., read the whole file at once?
Text or binary mode should be specified by the caller. The solution should be standard-compliant, portable and efficient. ...
wilbur_m
254
votes
15
answers
482k
views
How to append a char to a std::string?
The following fails with the error prog.cpp:5:13: error: invalid conversion from ‘char’ to ‘const char*’
int main()
{
char d = 'd';
std::string y("Hello worl");
y.append(d); // Line 5 - this ...
- 5,249
230
votes
12
answers
407k
views
Converting an int to std::string
What is the shortest way, preferably inline-able, to convert an int to a string? Answers using stl and boost will be welcomed.
- 78.1k
229
votes
20
answers
410k
views
C++ Convert string (or char*) to wstring (or wchar_t*)
string s = "おはよう";
wstring ws = FUNCTION(s, ws);
How would i assign the contents of s to ws?
Searched google and used some techniques but they can't assign the exact content. The content is ...
- 4,033
220
votes
20
answers
310k
views
How do I create a random alpha-numeric string in C++?
I'd like to create a random string, consisting of alpha-numeric characters. I want to be able to be specify the length of the string.
How do I do this in C++?
- 23.6k
219
votes
8
answers
774k
views
std::cin input with spaces?
#include <string>
std::string input;
std::cin >> input;
The user wants to enter "Hello World". But cin fails at the space between the two words. How can I make cin take in the whole of ...
- 22.8k
217
votes
8
answers
101k
views
What's the difference between istringstream, ostringstream and stringstream? / Why not use stringstream in every case?
When would I use std::istringstream, std::ostringstream and std::stringstream and why shouldn't I just use std::stringstream in every scenario (are there any runtime performance issues?).
Lastly, is ...
- 2,395
216
votes
9
answers
536k
views
How to use printf with std::string
My understanding is that string is a member of the std namespace, so why does the following occur?
#include <iostream>
int main()
{
using namespace std;
string myString = "Press ENTER ...
- 17k
206
votes
19
answers
499k
views
How do I convert a double into a string in C++?
I need to store a double as a string. I know I can use printf if I wanted to display it, but I just want to store it in a string variable so that I can store it in a map later (as the value, not the ...
- 402k
200
votes
3
answers
46k
views
Meaning of acronym SSO in the context of std::string
In a C++ question about optimization and code style, several answers referred to "SSO" in the context of optimizing copies of std::string. What does SSO mean in that context?
Clearly not "single sign ...
- 47.8k
197
votes
21
answers
343k
views
How do you reverse a string in place in C or C++?
How do you reverse a string in C or C++ without requiring a separate buffer to hold the reversed string?
uvote
195
votes
7
answers
305k
views
193
votes
25
answers
514k
views
How do I concatenate multiple C++ strings on one line?
C# has a syntax feature where you can concatenate many data types together on 1 line.
string s = new String();
s += "Hello world, " + myInt + niceToSeeYouString;
s += someChar1 + interestingDecimal + ...
- 39k
182
votes
4
answers
235k
views
How do I convert from stringstream to string in C++?
How do I convert from std::stringstream to std::string in C++?
Do I need to call a method on the string stream?
- 39k
181
votes
9
answers
399k
views
How can I create a string from a single character?
I have a single char value, and I need to cast/convert it to a std::string. How can I do this?
I know how to go the opposite way, to retrieve a char from a std::string object: you just need to index ...
- 2,699
180
votes
11
answers
330k
views
C++ deprecated conversion from string constant to 'char*'
I have a class with a private char str[256];
and for it I have an explicit constructor:
explicit myClass(char *func)
{
strcpy(str,func);
}
I call it as:
myClass obj("example");
When I ...
- 2,361
166
votes
18
answers
386k
views
Parsing a comma-delimited std::string [duplicate]
If I have a std::string containing a comma-separated list of numbers, what's the simplest way to parse out the numbers and put them in an integer array?
I don't want to generalise this out into ...
164
votes
21
answers
105k
views
Conveniently Declaring Compile-Time Strings in C++
Being able to create and manipulate strings during compile-time in C++ has several useful applications. Although it is possible to create compile-time strings in C++, the process is very cumbersome, ...
- 14.5k
156
votes
5
answers
192k
views
stringstream, string, and char* conversion confusion
My question can be boiled down to, where does the string returned from stringstream.str().c_str() live in memory, and why can't it be assigned to a const char*?
This code example will explain it ...
- 9,910
152
votes
7
answers
300k
views
Difference between string and char[] types in C++
For C, we use char[] to represent strings.
For C++, I see examples using both std::string and char arrays.
#include <iostream>
#include <string>
using namespace std;
int main () {
...
- 2,056