Difference between revisions of "Peer Legacy ECE264" - Rhea

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-'''Important information you should know if you come from CS159'''
-In CS159, students are taught that the main function is defined as follows:
-(hash)include <stdio.h>
-int main()
-{
-    ... (rest of code here)
-    return 0;
-}
-Instead of this, you can put in arguments in the main function:
-(hash)include <stdio.h>
-int main( int argc, char *argv[] ) {
-     ... (rest of code here)
-     return 0;
-}
-Here, int argc is the number of arguments ( '''[[arg]]'''ument  '''[[c]]'''ount ) given when you compile the code using gcc.
-For example:
-$ gcc example1.c
-$ ./a.out
-Also note "./a.out" is analogous to a.out used in CS159. Also, here int argc has a value of 1, where "./a.out" also counts as a argument.
-Note that we can have more than 1 argument (like filename, output filename, etc.).
-"char *argv[]" is an array containing all the arguments entered by the user ('''[[arg]]'''ument '''[[v]]'''alue). So therefore, in the above example, "./a.out" is argv[0], and so on.
-The length of "char *argv[]" is always int argc.
-These two arguments can be used to get important information from the user without using the scanf function. This has many applications,
-especially in this course and later on.
-Also, regarding the return value of the main function, it doesn't always have to be 0. It can be any integer. Conventionally, if a program gives out
-the expected result, the return value is 0, and if something goes wrong, the return value is -1.

Revision as of 21:12, 26 April 2011