Here is a selection:
int main(int argc, char *argv[])
{
if (argc > 1)
return 5;
else
return 7;
return 0;
}
After "toggle comment", I'd like to see this:
int main(int argc, char *argv[])
{
// if (argc > 1)
// return 5;
// else
return 7;
return 0;
}
How to do it?
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I have a situation where it would be helpful to be able to add blocks to an inactive queue which is then activated after another event happens. However, the entire thread from which I call dispatch_sync gets locked if the dispatch queue is suspended/inactive.
Is something like this possible? If not what other options do I have?
An example (not my actual use case):
#include <stdio.h>
#import <dispatch/dispatch.h>
int main(int argc, const char * argv[]) {
dispatch_queue_t my_queue = dispatch_queue_create("my_queue", DISPATCH_QUEUE_SERIAL_INACTIVE);
void (^b)(int) = ^void(int c) {
printf("%i\n", c);
};
for(int i = 1; i <= 1000; i++) {
dispatch_sync(my_queue, ^{ b(i); });
}
dispatch_activate(my_queue);
return 0;
}
I figured it out. Using dispatch_async fixed the problem.
Working solution:
#include <stdio.h>
#import <dispatch/dispatch.h>
int main(int argc, const char * argv[]) {
dispatch_queue_t my_queue = dispatch_queue_create("my_queue", DISPATCH_QUEUE_SERIAL_INACTIVE);
void (^b)(int) = ^void(int c) {
printf("%i\n", c);
};
for(int i = 1; i <= 1000; i++) {
dispatch_async(my_queue, ^{ b(i); });
}
dispatch_activate(my_queue);
return 0;
}
Here I need to write a function which is called from main method with integer array as a parameter please give me example.
In below example parameter are int type.
Note : please tell this is correct way to do this or not...
#import <Foundation/Foundation.h>
void displayit (int);
int main (int argc, const char * argv[])
{
#autoreleasepool {
int i;
for (i=0; i<5; i++)
{
displayit( i );
}
}
return 0;
}
void displayit (int i)
{
int y = 0;
y += i;
NSLog (#"y + i = %i", y);
}
Thanks in advance....
I tried out these, please check.
#import <Foundation/Foundation.h>
void displayit (int array[], int len);
int main (int argc, const char * argv[])
{
#autoreleasepool {
int array[]={1,2,3};
displayit( array, 3 );
}
return 0;
}
void displayit (int array[], int len)
{
for(int i=0;i<len;i++){
NSLog(#"display %d : %d",i,array[i]);
}
}
The out put is:
2014-10-30 14:09:32.017 OSTEST[32541:77397] display 0 : 1
2014-10-30 14:09:32.018 OSTEST[32541:77397] display 1 : 2
2014-10-30 14:09:32.018 OSTEST[32541:77397] display 2 : 3
Program ended with exit code: 0
I used another parameter len to avoid boundary beyond.
If the array is a global, static, or automatic variable (int array[10];), then sizeof(array)/sizeof(array[0]) works. Quoted From Another Question
I'm completely new to Objective C and I'm trying to use it to wrap a C-library. I have a main.m wrap.m and wrap.h files. From what I gather in the header file I included #interface and in the source file I will include #implementation However I'm not really understanding what to include in each of them. Right now my main file is:
int copy_data(struct archive *ar, struct archive *aw) {
for (;;) {
const void *buff;
size_t size;
off_t offset;
int r = archive_read_data_block(ar, &buff, &size, &offset);
if (r == ARCHIVE_EOF)
return (ARCHIVE_OK);
archive_write_data_block(aw, buff, size, offset);
}
}
int main(int argc, const char * argv[])
{
#autoreleasepool {
struct archive *a;
struct archive *ext;
struct archive_entry *entry;
int flags;
int r;
/* Select which attributes we want to restore. */
flags = ARCHIVE_EXTRACT_TIME;
flags |= ARCHIVE_EXTRACT_PERM;
flags |= ARCHIVE_EXTRACT_ACL;
flags |= ARCHIVE_EXTRACT_FFLAGS;
a = archive_read_new();
archive_read_support_format_all(a);
archive_read_support_compression_all(a);
ext = archive_write_disk_new();
archive_write_disk_set_options(ext, flags);
archive_write_disk_set_standard_lookup(ext);
r = archive_read_open_filename(a, argv[1], 10240);
for (;;) {
r = archive_read_next_header(a, &entry);
if (r == ARCHIVE_EOF)
break;
r = archive_write_header(ext, entry);
if (archive_entry_size(entry) > 0) {
copy_data(a, ext);
}
archive_write_finish_entry(ext);
}
archive_read_close(a);
archive_read_free(a);
archive_write_close(ext);
archive_write_free(ext);
NSLog(#"No Issues");
}
return 0;
}
So far what I'm getting in my wrap.h file is:
typedef struct{
int *a;
int *ext;
}archive;
#interface main : NSObject
#property int flags;
#property int r;
I don't know if that is close to what I need to do, and I'm getting errors on my ARCHIVE_EXTRACT saying they are undeclared identifiers which I assume also have to go into my wrap.h file but I'm not sure how to do that. Any help at all would be appreciated!
If you start your project in Xcode using the CommandLineTool template, you can select your language to be "C" or "C++", so you wouldn't have to mess with Objective-C at all.
As for the .h file that you currently have, don't do "#property" or "#interface" for "main". "main" is a C style function and not an Objective-C thing.
If you are actually interested in an objectivec solution, follow Michael Dautermann's instructions to start a new Command Line project but instead of Type C use the Foundation option. This will give you a working main (just a regular c function). Then select new->objective c class to create your wrap.h/wrap.m. In the wrap.h you will pretty much exclusively be declaring your own objectivec public wrapper methods. In the wrap.m, you'll be importing what you want to wrap, and defining your wrapper functions.
//
// main.m
//
#import <Foundation/Foundation.h>
#import "wrap.h"
int main(int argc, const char * argv[])
{
#autoreleasepool {
[wrap wrappedStuff];
}
return 0;
}
//
// wrap.h
//
----------
#import <Foundation/Foundation.h>
#interface wrap : NSObject
+ (void)wrappedStuff;
#end
//
// wrap.m
//
#import "wrap.h"
#include "WhatImWrapping.h"
#implementation wrap
int copy_data(struct archive *ar, struct archive *aw) {
for (;;) {
const void *buff;
size_t size;
off_t offset;
int r = archive_read_data_block(ar, &buff, &size, &offset);
if (r == ARCHIVE_EOF)
return (ARCHIVE_OK);
archive_write_data_block(aw, buff, size, offset);
}
}
+ (void)wrappedStuff
{
struct archive *a;
struct archive *ext;
struct archive_entry *entry;
int flags;
int r;
/* Select which attributes we want to restore. */
flags = ARCHIVE_EXTRACT_TIME;
flags |= ARCHIVE_EXTRACT_PERM;
flags |= ARCHIVE_EXTRACT_ACL;
flags |= ARCHIVE_EXTRACT_FFLAGS;
a = archive_read_new();
archive_read_support_format_all(a);
archive_read_support_compression_all(a);
ext = archive_write_disk_new();
archive_write_disk_set_options(ext, flags);
archive_write_disk_set_standard_lookup(ext);
r = archive_read_open_filename(a, argv[1], 10240);
for (;;) {
r = archive_read_next_header(a, &entry);
if (r == ARCHIVE_EOF)
break;
r = archive_write_header(ext, entry);
if (archive_entry_size(entry) > 0) {
copy_data(a, ext);
}
archive_write_finish_entry(ext);
}
archive_read_close(a);
archive_read_free(a);
archive_write_close(ext);
archive_write_free(ext);
NSLog(#"No Issues");
}
#end
I'm doing a tutorial from this book: "Objective-C 2.0 Essentials 3rd edition" by Neil Smyth. I have tried repeatedly but keep getting the same "Expected expression" error even though the books version claims to run. I've checked way too many times and my version is exactly the same as the books. Please, can someone help me. Code below:
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
#autoreleasepool {
int x;
int j = 54321;
for (x = 0; x < 10; x++) {
}
int j = x + 10;
NSLog (#"Variable j in for loop is %i", j);
NSLog (#"Variable j outside for loop is %i", j); /* I GET AN ERROR STATING " EXPECTED EXPRESSION HERE*/
}
return 0;
}
The line
NSLog (#"Variable j outside for loop is %i", j);
contains a lot of invisible characters (UTF-8 sequence EF BF BC = OBJECT REPLACEMENT CHARACTER) between the Tab and the "NSLog".
Deleting and rewriting that line should help.
OP's code opened in hexa editor:
Format your code better; if you do the misplaced } in the code becomes obvious:
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
#autoreleasepool {
int x;
int j = 54321;
for (x = 0; x < 10; x++) {
int j = x + 10;
NSLog (#"Variable j in for loop is %i", j);
}
 NSLog (#"Variable j outside for loop is %i", j);
}
return 0;
}
EDIT The invisible characters as pointed out by #MartinR are also an issue (that I didn't notice). So there are two errors in your code.
Exercise:
Write a program that converts 27° from degrees Fahrenheit (F) to degrees Celsius
(C) using the following formula:
C = (F - 32) / 1.8
Note that you don’t need to define a class to perform this calculation. Simply evaluating
the expression will suffice.
Here is my code:
#import <Foundation/Foundation.h>
int main (int argc, const char *argv[])
{
NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init];
float C;
float F;
F = 27;
C=(F-32)/1.8;
NSLog (#"27 degrees Fahrenheit is %f degrees Celsius." , C);
[drain pool];
return 0;
}
"Build failed"
On official forum there is a suggestion to write it this way :
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
double C, F;
F=27;
C=(F-32)/1.8;
int c=C;
NSLog(#"%g degrees Fahrenheit equals %i centigrades!", F, c);
[pool drain];
return 0;
}
But it also gives me "Failed" message.
What is not correct?
Update
Problem resolved.
I didn't set up initial settings of my project properly.
I was working inside other "C" programming language project.
I had to just create new project-> OS X -> Command line tool (type: Foundation) unmark "Use Automatic Reference Counting"
But the best part- i was rewarded with successfully compiled program:
2012-08-09 00:20:29.214 4.2[19452:403] 27 degrees Fahrenheit is -2.777778 degrees Celsius.
Thank you #trojanfoe , #john.k.doe , #drewk , #hol
This works:
#import <Foundation/Foundation.h>
int main(int argc, const char * argv[])
{
#autoreleasepool {
float C;
float F;
F = 27.0;
C=(F-32.0)/1.8;
NSLog (#"27 degrees Fahrenheit is %f degrees Celsius." , C);
}
return 0;
}
So does this:
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
double F=27.2;
double C=(F-32.0)/1.8;
NSLog(#"%g degrees Fahrenheit equals %g centigrade!", F, C);
[pool drain];
return 0;
}
As you are not using objects even this will do it. Plain C.
int main(int argc, const char * argv[])
{
double C, F;
F=27;
C=(F-32)/1.8;
int c=C;
printf("%g degrees Fahrenheit equals %i centigrades!", F, c);
return 0;
}
Do you need to parse the arguments and calculate based on those?