use C++ style casts instead of C style casts and the answer is obvious 2. const_cast<char *>(s.c_str());

#include<iostream> #include<cstring> using namespace std; string extractStringAtKey(string str,int key){ char* s=strtok((char*)str.c_str()," "); while(key>1){ s=strtok(NULL," "); key--; } return (string)s; } int main(){ string s("10 20 30 40"); int key; cin>>key; cout<<extractStringAtKey(s,key); } Above program is working fine.But i have a doubt why cant we simply use str.c_str() instead of (char*)str.c_str() in the function strtok( , " ").

#include<iostream> #include<cstring> using namespace std; string extractStringAtKey(string str,int key){ char* s=strtok((char*)str.c_str()," "); while(key>1){ s=strtok(NULL," "); key--; } return (string)s; } int main(){ string s("10 20 30 40"); int key; cin>>key; cout<<extractStringAtKey(s,key); } Above program is working fine.But i have a doubt why cant we simply use str.c_str() instead of (char*)str.c_str() in the function strtok( , " ").

#include<iostream> #include<cstring> using namespace std; string extractStringAtKey(string str,int key){ char* s=strtok((char*)str.c_str()," "); while(key>1){ s=strtok(NULL," "); key--; } return (string)s; } int main(){ string s("10 20 30 40"); int key; cin>>key; cout<<extractStringAtKey(s,key); } Above program is working fine.But i have a doubt why cant we simply use str.c_str() instead of (char*)str.c_str() in the function strtok( , " ").

If is_open failed then you should not continue with the rest of the operations. If you do, you will only see garbage values (undefined behavior) You should do something like this if(!inFile.is_open()){ cerr << "File opening for read failed"; exit(1); //or throw an exception } else { //rest of your code }

#include<iostream> #include<cstring> using namespace std; string extractStringAtKey(string str,int key){ char* s=strtok((char*)str.c_str()," "); while(key>1){ s=strtok(NULL," "); key--; } return (string)s; } int main(){ string s("10 20 30 40"); int key; cin>>key; cout<<extractStringAtKey(s,key); } Above program is working fine.But i have a doubt why cant we simply use str.c_str() instead of (char*)str.c_str() in the function strtok( , " ").

also while you are at it, maybe replace the C style function with something more appropriate for C++ https://stackoverflow.com/questions/53849/how-do-i-tokenize-a-string-in-c (read multiple answers, not just the top one)

actually i am a beginner ,finding hard to understand your point Btw thanks i'll consider this.

your program exhibits undefined behaviour. you are not supposed to modify the string through the pointer provided by c_str(). it is const for a reason.

This, u trying to tell something about pointer to const,, and pointer to non-const

Help me please; Qsn. A programmer created a programme for a hospital bill to store patient details as a single entity consisting of:PatientNo, Patient_Name,Gender and Age. i: identify the most appropriate data structure the programmer could have used. ii:using C language,declare a data structure that could be used to store this data

c_str() returns a const char *, using that pointer to modify the string is undefined behaviour.

show the code you have done and where you are stuck

use the data() member function if you want a pointer to non-const

First am confused which data structure am going to use,,if only I understand that data structure am able to do the rest

For what he is doing, using data() (the non const version) will also result in Undefined Behavior

#include<iostream> #include<cstring> using namespace std; string extractStringAtKey(string str,int key){ char* s=strtok((char*)str.c_str()," "); while(key>1){ s=strtok(NULL," "); key--; } return (string)s; } int main(){ string s("10 20 30 40"); int key; cin>>key; cout<<extractStringAtKey(s,key); } Above program is working fine.But i have a doubt why cant we simply use str.c_str() instead of (char*)str.c_str() in the function strtok( , " ").

#include<stdio.h> #include<string.h> struct bill { char patient_name[2]; int age; int patientNo; char gender; } int main(){ struct patient_name; strcpy(patient name,""); patientNo=; gender=; age=; printf("name=%s\n",patient_name); printf("patientNo=%s\n",patientNo); printf("age=%d\n",age); printf("gender=%c\n",gender); return 0; }

Learn C seriously, instead of just stringing random characters together until it compiles.

#ASK I have a project with some header and source files, under 3-5. It is still convenient to include them (.c source files) in the compile command, but what if i have 20 header and its source files? how can i handle such situation?

You can separate the compilation unit with -c flag, after you got all sources compiled, you can link them together into single binary. So for example, you have a.c, b.c, and c.c. gcc -c a.c -o a.o gcc -c b.c -o b.o gcc -c c.c -o c.o gcc a.o b.o c.o -o bin

#ASK I have a project with some header and source files, under 3-5. It is still convenient to include them (.c source files) in the compile command, but what if i have 20 header and its source files? how can i handle such situation?

this is actually redundant, i can just do gcc main.c a.c b.c c.c -o bin I need something that can search for the x.c of x.h in a directory, is that actually possible?

this is actually redundant, i can just do gcc main.c a.c b.c c.c -o bin I need something that can search for the x.c of x.h in a directory, is that actually possible?

use CMake https://blog.feabhas.com/2021/07/cmake-part-1-the-dark-arts/

i want to cross-compile

> I need something that can search for the x.c of x.h in a directory, is that actually possible? Do you mean include path? You may be looking for -I flag.

Yes you can do it in single command, but in presence of multiple files, it can slow down your development, because when you make a change to a single file, you have to compile everything from zero + link it again. If you separate the compilation, you only need to recompile changed files and link it.

Hello, got an interesting case I`ve got uint8_t v1 and int8_t v2 variables uint8_t res Then I do following v1 = 75 v2 = -20 And after res = v1 + v2 //this gave me res equal to 55 as expected BUT while using macros, like this one MIN(a, b) ((a) > (b) ? (b) : (a)) MAX(a, b) ((a) > (b) ? (a) : (b)) LIMIT(a, min, max) (MIN(MAX((a), (min)), (max))) res = LIMIT(v1 + v2 , 0, 100) // this one returns me 100 to res Does C have some strange types cast in macros?

even with using limit macro?

even with using limit macro?

I want to know if anyone in this group already had worked with C++ in embedded systems

it might be better to ask you question instead asking if someone has worked with x, there are 14k members so it's highly probable (+ i think i have seen this topic here :) )

Thks, i will search about it in the group, if I don't find my question I will come back ask

How can we input an Array without any loops

Why has my question been deleted?

Oh np

input all bytes at once

so sorry, i was deleting messages and i didn't catch that someone has posted a message meanwhile i was deleting them, sorry @tuxifan 's Question: does rlimit RLIMIT_AS limit space allocated by brk() too?

Can you elaborate suppose I want to input 10 int in a[10]

Yes, according to man 2 getrlimit. RLIMIT_AS This is the maximum size of the process's virtual memory (address space). The limit is specified in bytes, and is rounded down to the system page size. This limit affects calls to brk(2), mmap(2), and mremap(2), which fail with the error ENOMEM upon exceeding this limit.

Who knows arrays well in c

only if the string gets reallocated in between the strtok() calls, right?

#include <stdio.h> int main(int argc, char *argv[]) { int n=0; int summe=0; printf("Eingabe der Variable n \n\n"); scanf("n= %i \n",&n); summe=n*(n+1)/2; printf("Die summe= %i \n",summe); printf("Press enter to continue ..."); fflush(stdin); getchar(); return 0; }

can anyone say me where is the wrong?

I see... I am not sure but isn't %d supposed to be for digit?