If a same macro is defined in so many files( let's say .CPP) . And we want to make change in its value such that it is reflected everywhere! Is there any way we can do it in one go rather than individually changing in each file

C++ enforces not to use macros at any level, the exception is only for header guards

If a same macro is defined in so many files( let's say .CPP) . And we want to make change in its value such that it is reflected everywhere! Is there any way we can do it in one go rather than individually changing in each file

There is this concept called DRY in software engineering. It means "Don't Repeat Yourself". Since your code violates that principle, you have to now pay the price.

what mistake is there while printing friquency in this code?

cin >> n[10]; This does not accept input into an array of 10 elements like you think. This accepts input only into one location i.e. n[10]. Moreover n[10] is an invalid location because your array has elements only in positions 0 to 9. You have to use a for loop to accept inputs into the array.

anyone please illustrate this syntax: for(int i = 1; i <= (input-'A'+1); ++i)

anyone please illustrate this syntax: for(int i = 1; i <= (input-'A'+1); ++i)

That’s the condition set for a for loop. It means that the code inside that loop will continue until i passes above input - ‘A’ + 1.

That’s the condition set for a for loop. It means that the code inside that loop will continue until i passes above input - ‘A’ + 1.

I'm not understanding "input-'A'+1" how does it work??

I'm not understanding "input-'A'+1" how does it work??

Unless you tell me what the variables input and ‘A’ are supposed to mean, I can’t help you.

Unless you tell me what the variables input and ‘A’ are supposed to mean, I can’t help you.

Ok I'm sending you the source code

I'm not understanding "input-'A'+1" how does it work??

Code point of the letter 'A' according to ASCII is 65. So, it is actually input-65+1

Ok I'm sending you the source code

Where?

Where?

Saurav Shri sent a code, it has been re-uploaded as a file

cin >> n[10]; This does not accept input into an array of 10 elements like you think. This accepts input only into one location i.e. n[10]. Moreover n[10] is an invalid location because your array has elements only in positions 0 to 9. You have to use a for loop to accept inputs into the array.

Oh yeh thankyou sir for. Reminder

Code point of the letter 'A' according to ASCII is 65. So, it is actually input-65+1

OO it means it directly use the ASCII value of A rather than as we usually use 'int' as input and convert it into 'char'

Ok I'm sending you the source code

Apparently, your program outputs the number of each letter that number of times (A = 1, B = 2, C = 3, etc.).

OO it means it directly use the ASCII value of A rather than as we usually use 'int' as input and convert it into 'char'

Right

Right

thanks, I got it.

Hi, does anyone know why im getting the error "expected declaration or statement at the end of input"? Here's the part of my code: for(i=0; i<num; i++) { fprintf(fp, "%d %s %s %s %s %s %s\n",sPui[i].puiid, sPui[i].name, sPui); }

Hi, does anyone know why im getting the error "expected declaration or statement at the end of input"? Here's the part of my code: for(i=0; i<num; i++) { fprintf(fp, "%d %s %s %s %s %s %s\n",sPui[i].puiid, sPui[i].name, sPui); }

You have 6 % masks and only passed 3 arguments

Hi, does anyone know why im getting the error "expected declaration or statement at the end of input"? Here's the part of my code: for(i=0; i<num; i++) { fprintf(fp, "%d %s %s %s %s %s %s\n",sPui[i].puiid, sPui[i].name, sPui); }

it's hard to say from such short code but it seems you are printing 7 arguments but pass only 3 values

```c

Rida 2015 sent a code, it has been re-uploaded as a file

can someone compile this code and give me the output

it should be going from 00 01,...,98 99 to this

its c not c++

can someone compile this code and give me the output

> int b = a; > for (b = 0; ...) ?

its c not c++

What's the output of strace ? and why not pass the the reference of c ?

what strace u talking about

> int b = a; > for (b = 0; ...) ?

that just a normal for loop what ?

what strace u talking about

You experimenting with system call and you didn't know about strace ?

no i dont know about strace

that just a normal for loop what ?

if b is defined inside loop, why would you put int b = a ?

what u talking about

i define b in line 12

before the first for loop

oh u can remove the int in line 15

keep it only b = a

Also, 0 char on ASCII table is represented as 48 value, but the a is started from -1

lol a friend told me it give him 98 99 is that true ?

bro read the code or don't commet about it

if u read the code u gonna see that when i call them i add 48

look at line 19 and 20 +++

48 + a

and yes i can make a a char but i choose to make it an int because i can add 48 on it

48 + a

a is started from -1, 0 on ascii table is started from 48. 48 + (-1) is what ?

You can't expect to print raw byte to get printed on console

it start from -1 but in the first loop it will get increment

i hava done this in while loop and it work perfect

im only playing with the code because i have more time

can u just confirm the output of the code for me

then we can continue

can u just confirm the output of the code for me

Oww, sorry. The output is 98 99

Did you make typos at for (a = -1;a < 98;a++); notice the semicolon

Oww, sorry. The output is 98 99

does it give only this out put no numbers before it ?

like 00 01 00 02...

lol yeah remove those semicolon please

does it give only this out put no numbers before it ?

There maybe more stuff on stdout but the console will display the output if it's recognized.

like 00 01 00 02...

No

remove the semicolon in line 13 and line 16 and run the code

sorry i mean compile and run it

remove the semicolon in line 13 and line 16 and run the code

Can't you just use online compiler '-')/ ?

Most of online compilers are hosted on Linux which has support for unistd.h headers

Can't you just use online compiler '-')/ ?

don't u think if i could do that i would have done it ?

Is it the way you ask for help to others ? Please calm down if you're feel stressed out

After learning data structures and algorithm, what can I do with c++ apart from video games

Anything

stdin, stdout and stderr are files to unix-based systems, but are they considered files on windows and other systems?

stdin, stdout and stderr are files to unix-based systems, but are they considered files on windows and other systems?

On Windows, They're using Everything is Object instead of file (descriptor) concept. Everything on Windows is managed by things called HANDLE instead of fd

Each of Windows process has own ProcessEnvironmentBlock, The Standard HANDLE is accessed from RTL_USER__PROCESS_PARAMETERS

Also read this one https://devblogs.microsoft.com/commandline/windows-command-line-inside-the-windows-console/

Also read this one https://devblogs.microsoft.com/commandline/windows-command-line-inside-the-windows-console/

thank you!

what is the proper way of handling errors here? while (1) { int ch = getc(file); if (ch == EOF) break; putc(ch, stdout); } should i check for ferror every iteration of the loop? and also i believe I should fflush inside the if and check for error again, right? since stdout is buffered by default

what is the proper way of handling errors here? while (1) { int ch = getc(file); if (ch == EOF) break; putc(ch, stdout); } should i check for ferror every iteration of the loop? and also i believe I should fflush inside the if and check for error again, right? since stdout is buffered by default

stdout is line buffered more exactly,

stdout is line buffered more exactly,

yep

If you need to build a list of args to pass to execvp which is the most meaningful and common? char *a[1024] or char **a followed of realloc as it grows?

I'm asking because 1. I need to guess that the array has 1024 positions to be sufficiently large... but it is still not secure if it has 1025, and if I have just 1 I'm allocating other unnecessary 1023 slots. 2. If I use malloc/realloc and execvp successfully replaces the process a further free() will never be called

I'm asking because 1. I need to guess that the array has 1024 positions to be sufficiently large... but it is still not secure if it has 1025, and if I have just 1 I'm allocating other unnecessary 1023 slots. 2. If I use malloc/realloc and execvp successfully replaces the process a further free() will never be called

If I use malloc/realloc and execvp successfully replaces the process a further free() will never be called Why do you care? As a part of execvp, the memory image of the process is replaced completely. How does it matter whether the array allocated in original forked child process is freed or not. If the args array was built in the parent process, then you should still free it in the parent process.

Who knows OpenCV, encounter a problem will not be solved, just started to learn opencv, ask for advice

at matDst1, matDst2; cv::resize(matSrc1, matDst1, cv::Size(32, 32), 0, 0, cv::INTER_CUBIC); cv::resize(matSrc2, matDst2, cv::Size(32, 32), 0, 0, cv::INTER_CUBIC); cout<<"channels: "<<matDst1.channels()<<" type: "<<matDst1.type()<<endl; cv::cvtColor(matDst1, matDst1, COLOR_RGB2BGRA); cv::cvtColor(matDst2, matDst2, COLOR_RGB2BGRA); cout<<"channels: "<<matDst1.channels()<<" type: "<<matDst1.type()<<endl; matDst1.convertTo(matDst1, CV_32F); matDst2.convertTo(matDst2, CV_32F); cout<<"channels: "<<matDst1.channels()<<" type: "<<matDst1.type()<<endl; dct(matDst1, matDst1); dct(matDst2, matDst2);

channels: 3 type: 16 channels: 4 type: 24 channels: 4 type: 29 terminate called after throwing an instance of 'cv::Exception' what(): OpenCV(4.5.5) /home/zyq/opencv-4.5.5/modules/core/src/dxt.cpp:4417: error: (-215:Assertion failed) type == CV_32FC1 || type == CV_64FC1 in function 'dct' Aborted (core dumped)