Variadic string concatenation function in C
$begingroup$
Problem
I've been trying to create a variadic function that concatenates a group of strings together.
The function is to be sentinel-controlled (iterating through a sentinel argument stops the search for more arguments).
It's use case should be implicit and not require the user to add the sentinel value to the argument list.
Attempt
#include <stdarg.h>
#include <stdlib.h>
/* Concatenate Strings */
char* concatenate(char stringA, char stringB) { /* The code here works but is quite long... */ }
char* concatenate(char string, ...) {
char* argument = (char*) "";
va_list arguments;
va_start(arguments, string);
do {
argument = va_arg(arguments, char*);
string = concatenate(string, argument);
} while (NULL != argument);
va_end(arguments);
return string;
}
int main(int argc, char* argv) {
printf("%s", concatenate("A, ", "B, ", "C, ", "D"/*, NULL*/));
return 0;
}
Here's what I've got so far.
It all works when I add NULL to the end of the arguments, but as required of the solution, any sentinel value is supposed to be implicit (without adding NULL) i.e.:
concatenate("A", "B", "C") as opposed to concatenate("A", "B", "C", NULL)
Solution
The function should work implicitly.
I'm still not sure how and any help would be greatly appreciated.
Thanks for taking the time to read through this post.
c reinventing-the-wheel
edited 41 mins ago
esote
2,78611038
asked 1 hour ago
LapysLapys
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
Problem
I've been trying to create a variadic function that concatenates a group of strings together.
The function is to be sentinel-controlled (iterating through a sentinel argument stops the search for more arguments).
It's use case should be implicit and not require the user to add the sentinel value to the argument list.
Attempt
#include <stdarg.h>
#include <stdlib.h>
/* Concatenate Strings */
char* concatenate(char stringA, char stringB) { /* The code here works but is quite long... */ }
char* concatenate(char string, ...) {
char* argument = (char*) "";
va_list arguments;
va_start(arguments, string);
do {
argument = va_arg(arguments, char*);
string = concatenate(string, argument);
} while (NULL != argument);
va_end(arguments);
return string;
}
int main(int argc, char* argv) {
printf("%s", concatenate("A, ", "B, ", "C, ", "D"/*, NULL*/));
return 0;
}
Here's what I've got so far.
It all works when I add NULL to the end of the arguments, but as required of the solution, any sentinel value is supposed to be implicit (without adding NULL) i.e.:
concatenate("A", "B", "C") as opposed to concatenate("A", "B", "C", NULL)
Solution
The function should work implicitly.
I'm still not sure how and any help would be greatly appreciated.
Thanks for taking the time to read through this post.
c reinventing-the-wheel
edited 41 mins ago
esote
2,78611038
asked 1 hour ago
LapysLapys
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
$begingroup$
The function need to know where the parameter list ends. There are 2 possibilities to solve this: A sentinel parameter, which tells the function that it has the last element or a parameter at the beginning, which tells the function how many parameters will follow (like theprintfformat string or a simpleint).
$endgroup$
– mch
53 mins ago
$begingroup$
If your code does not work as you intend -- you say it currently does not work without a sentinel value -- then it is off-topic for Code Review.
$endgroup$
– esote
39 mins ago
$begingroup$
If these are just string literals then#define MERGE(...) __VA_ARGS__will do. Example:MERGE("hello" "world" "how" "are" "you")gives"helloworldhowareyou". You don't even need the macro.
$endgroup$
– Lundin
34 mins ago
add a comment |
$begingroup$
Problem
I've been trying to create a variadic function that concatenates a group of strings together.
The function is to be sentinel-controlled (iterating through a sentinel argument stops the search for more arguments).
It's use case should be implicit and not require the user to add the sentinel value to the argument list.
Attempt
#include <stdarg.h>
#include <stdlib.h>
/* Concatenate Strings */
char* concatenate(char stringA, char stringB) { /* The code here works but is quite long... */ }
char* concatenate(char string, ...) {
char* argument = (char*) "";
va_list arguments;
va_start(arguments, string);
do {
argument = va_arg(arguments, char*);
string = concatenate(string, argument);
} while (NULL != argument);
va_end(arguments);
return string;
}
int main(int argc, char* argv) {
printf("%s", concatenate("A, ", "B, ", "C, ", "D"/*, NULL*/));
return 0;
}
Here's what I've got so far.
It all works when I add NULL to the end of the arguments, but as required of the solution, any sentinel value is supposed to be implicit (without adding NULL) i.e.:
concatenate("A", "B", "C") as opposed to concatenate("A", "B", "C", NULL)
Solution
The function should work implicitly.
I'm still not sure how and any help would be greatly appreciated.
Thanks for taking the time to read through this post.
c reinventing-the-wheel
edited 41 mins ago
esote
2,78611038
asked 1 hour ago
LapysLapys
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
Problem
I've been trying to create a variadic function that concatenates a group of strings together.
The function is to be sentinel-controlled (iterating through a sentinel argument stops the search for more arguments).
It's use case should be implicit and not require the user to add the sentinel value to the argument list.
Attempt
#include <stdarg.h>
#include <stdlib.h>
/* Concatenate Strings */
char* concatenate(char stringA, char stringB) { /* The code here works but is quite long... */ }
char* concatenate(char string, ...) {
char* argument = (char*) "";
va_list arguments;
va_start(arguments, string);
do {
argument = va_arg(arguments, char*);
string = concatenate(string, argument);
} while (NULL != argument);
va_end(arguments);
return string;
}
int main(int argc, char* argv) {
printf("%s", concatenate("A, ", "B, ", "C, ", "D"/*, NULL*/));
return 0;
}
Here's what I've got so far.
It all works when I add NULL to the end of the arguments, but as required of the solution, any sentinel value is supposed to be implicit (without adding NULL) i.e.:
concatenate("A", "B", "C") as opposed to concatenate("A", "B", "C", NULL)
Solution
The function should work implicitly.
I'm still not sure how and any help would be greatly appreciated.
Thanks for taking the time to read through this post.
c reinventing-the-wheel
c reinventing-the-wheel
edited 41 mins ago
esote
2,78611038
asked 1 hour ago
LapysLapys
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 41 mins ago
esote
2,78611038
asked 1 hour ago
LapysLapys
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 41 mins ago
esote
2,78611038
edited 41 mins ago
esote
2,78611038
edited 41 mins ago
esote
2,78611038
2,78611038
asked 1 hour ago
LapysLapys
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
LapysLapys
992
asked 1 hour ago
LapysLapys
992
992
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Lapys is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$begingroup$
The function need to know where the parameter list ends. There are 2 possibilities to solve this: A sentinel parameter, which tells the function that it has the last element or a parameter at the beginning, which tells the function how many parameters will follow (like theprintfformat string or a simpleint).
$endgroup$
– mch
53 mins ago
$begingroup$
If your code does not work as you intend -- you say it currently does not work without a sentinel value -- then it is off-topic for Code Review.
$endgroup$
– esote
39 mins ago
$begingroup$
If these are just string literals then#define MERGE(...) __VA_ARGS__will do. Example:MERGE("hello" "world" "how" "are" "you")gives"helloworldhowareyou". You don't even need the macro.
$endgroup$
– Lundin
34 mins ago
add a comment |
$begingroup$
The function need to know where the parameter list ends. There are 2 possibilities to solve this: A sentinel parameter, which tells the function that it has the last element or a parameter at the beginning, which tells the function how many parameters will follow (like theprintfformat string or a simpleint).
$endgroup$
– mch
53 mins ago
$begingroup$
If your code does not work as you intend -- you say it currently does not work without a sentinel value -- then it is off-topic for Code Review.
$endgroup$
– esote
39 mins ago
$begingroup$
If these are just string literals then#define MERGE(...) __VA_ARGS__will do. Example:MERGE("hello" "world" "how" "are" "you")gives"helloworldhowareyou". You don't even need the macro.
$endgroup$
– Lundin
34 mins ago
$begingroup$
The function need to know where the parameter list ends. There are 2 possibilities to solve this: A sentinel parameter, which tells the function that it has the last element or a parameter at the beginning, which tells the function how many parameters will follow (like the
printf format string or a simple int).$endgroup$
– mch
53 mins ago
$begingroup$
The function need to know where the parameter list ends. There are 2 possibilities to solve this: A sentinel parameter, which tells the function that it has the last element or a parameter at the beginning, which tells the function how many parameters will follow (like the
printf format string or a simple int).$endgroup$
– mch
53 mins ago
$begingroup$
If your code does not work as you intend -- you say it currently does not work without a sentinel value -- then it is off-topic for Code Review.
$endgroup$
– esote
39 mins ago
$begingroup$
If your code does not work as you intend -- you say it currently does not work without a sentinel value -- then it is off-topic for Code Review.
$endgroup$
– esote
39 mins ago
$begingroup$
If these are just string literals then
#define MERGE(...) __VA_ARGS__ will do. Example: MERGE("hello" "world" "how" "are" "you") gives "helloworldhowareyou". You don't even need the macro.$endgroup$
– Lundin
34 mins ago
$begingroup$
If these are just string literals then
#define MERGE(...) __VA_ARGS__ will do. Example: MERGE("hello" "world" "how" "are" "you") gives "helloworldhowareyou". You don't even need the macro.$endgroup$
– Lundin
34 mins ago
add a comment |
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$begingroup$
The function need to know where the parameter list ends. There are 2 possibilities to solve this: A sentinel parameter, which tells the function that it has the last element or a parameter at the beginning, which tells the function how many parameters will follow (like the
printfformat string or a simpleint).$endgroup$
– mch
53 mins ago
$begingroup$
If your code does not work as you intend -- you say it currently does not work without a sentinel value -- then it is off-topic for Code Review.
$endgroup$
– esote
39 mins ago
$begingroup$
If these are just string literals then
#define MERGE(...) __VA_ARGS__will do. Example:MERGE("hello" "world" "how" "are" "you")gives"helloworldhowareyou". You don't even need the macro.$endgroup$
– Lundin
34 mins ago