argc | 易学教程

executing a process with argc=0

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问题 Is it possible to execute a process whose argc = 0? I need to execute a program but it is extremely important for its argc to be equal to 0. Is there a way to do that? I tried to put 2^32 arguments in the command line so that it appears as if argc = 0 but there is a maximum limit to the number of arguments. 回答1: You can write a program that calls exec directly; that allows you to specify the command-line arguments (including the program name) and lack thereof. 回答2: You may use linux system

Why does MPI_Init accept pointers to argc and argv?

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this is how we use MPI_Init function int main(int argc, char **argv) { MPI_Init(&argc, &argv); … } why does MPI_Init use pointers to argc and argv instead of values of argv? NickTee According to the answer stated here: Passing arguments via command line with MPI Most MPI implementations will remove all the mpirun-related arguments in this function so that, after calling it, you can address command line arguments as though it were a normal (non-mpirun) command execution. i.e. after mpirun -np 10 myapp myparam1 myparam2 argc = 7(?) because of the mpirun parameters (it also seems to add some) and

Why does MPI_Init accept pointers to argc and argv?

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问题 this is how we use MPI_Init function int main(int argc, char **argv) { MPI_Init(&argc, &argv); … } why does MPI_Init use pointers to argc and argv instead of values of argv? 回答1: According to the answer stated here: Passing arguments via command line with MPI Most MPI implementations will remove all the mpirun-related arguments in this function so that, after calling it, you can address command line arguments as though it were a normal (non-mpirun) command execution. i.e. after mpirun -np 10

Process argc and argv outside of main()

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问题 If I want to keep the bulk of my code for processing command line arguments out of main (for organization and more readable code), what would be the best way to do it? void main(int argc, char* argv[]){ //lots of code here I would like to move elsewhere } 回答1: Either pass them as parameters, or store them in global variables. As long as you don't return from main and try to process them in an atexit handler or the destructor of an object at global scope, they still exist and will be fine to

Why is argc not a constant?

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int main( const int argc , const char[] const argv) As Effective C++ Item#3 states "Use const whenever possible", I start thinking "why not make these 'constant' parameters const "?. Is there any scenario in which the value of argc is modified in a program? In this case, history is a factor. C defined these inputs as "not constant", and compatibility with (a good portion of) existing C code was an early goal of C++. Some UNIX APIs, such as getopt , actually do manipulate argv[] , so it can't be made const for that reason also. (Aside: Interestingly, although getopt 's prototype suggests it won

Why is argc not a constant?

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问题 int main( const int argc , const char[] const argv) As Effective C++ Item#3 states "Use const whenever possible", I start thinking "why not make these 'constant' parameters const "?. Is there any scenario in which the value of argc is modified in a program? 回答1: In this case, history is a factor. C defined these inputs as "not constant", and compatibility with (a good portion of) existing C code was an early goal of C++. Some UNIX APIs, such as getopt , actually do manipulate argv[] , so it

Regarding 'main(int argc, char *argv[])' [duplicate]

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Possible Duplicates: What are the arguments to main() for? What does int argc, char *argv[] mean? Every program is starting with the main(int argc, char *argv[]) definition. I don't understand what it means. I would be very glad if somebody could explain why we use these arguments if we don't use them in the program? Why not just: int main() ? Is the name of the program one of the elements of *argv[] and argc is the count of the number of arguments in *argv[] ? What are the other arguments sent to *argv[] ? How do we send them? Frank The arguments argc and argv of main is used as a way to send

Regarding 'main(int argc, char *argv[])' [duplicate]

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问题 This question already has answers here : Closed 9 years ago . Possible Duplicates: What are the arguments to main() for? What does int argc, char *argv[] mean? Every program is starting with the main(int argc, char *argv[]) definition. I don\'t understand what it means. I would be very glad if somebody could explain why we use these arguments if we don\'t use them in the program? Why not just: int main() ? Is the name of the program one of the elements of *argv[] and argc is the count of the

What does int argc, char *argv[] mean?

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问题 In many C++ IDE\'s and compilers, when it generates the main function for you, it looks like this: int main(int argc, char *argv[]) When I code C++ without an IDE, just with a command line compiler, I type: int main() without any parameters. What does this mean, and is it vital to my program? 回答1: argv and argc are how command line arguments are passed to main() in C and C++. argc will be the number of strings pointed to by argv . This will (in practice) be 1 plus the number of arguments, as