It will look like int main(int argc, char *argv[]);
. My questions are:
1 How many array items can I add in argv[]
?
2 What is MAX size of every char *
?
Command-line arguments are given after the name of the program in command-line shell of Operating Systems. To pass command line arguments, we typically define main () with two arguments : first argument is the number of command line arguments and second is list of command-line arguments. int main (int argc, char *argv []) { /* ... */ }
Command line arguments in C/C++. The most important function of C/C++ is main () function. It is mostly defined with a return type of int and without parameters : int main () { /* ... */ }.
The command line arguments are handled using main() function arguments where argc refers to the number of arguments passed, and argv is a pointer array which points to each argument passed to the program.
In C, we can supply arguments to 'main' function. The arguments that we pass to main ( ) at command prompt are called command line arguments. These arguments are supplied at the time of invoking the program. The first argument argc is known as 'argument counter'. It represents the number of arguments in the command line.
You can try:
$ getconf ARG_MAX
2180000
http://pubs.opengroup.org/onlinepubs/007904975/basedefs/limits.h.html
ARG_MAX is maximum length of argument to the exec functions including environment data.
That is, there is no individual limit on the number of arguments or argument's length. Only the limit on total size required to store all the arguments and environment variables.
xargs
figures out maximum command line length using sysconf(_SC_ARG_MAX);
which yields the same value as reported by getconf ARG_MAX
.
On Linux command line arguments and environment variables are put into new process' stack. So, the process/thread maximum stack size is the ultimate upper bound. Linux-specific limits are hardcoded in the kernel:
#define MAX_ARG_STRLEN (PAGE_SIZE * 32)
#define MAX_ARG_STRINGS 0x7FFFFFFF
Both of those are bounded only by how much memory you have (or how much memory your OS gives your program).
EDIT: Actually, the number of arguments is also bounded by the size of int
.
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