I have to avoid double spaces, double ! and double full stops in my character array. I must have to use character array btw.
e.g Valid data: "It is raining.!" Invalid Data: "It is raining!!." (it is only example)
I tried the following way but am not getting desired result. Plz help me.
#include<iostream>
using namespace std;
bool isValidData( char data[60] );
int main()
{
char data[60];
cin.getline(data,60);
bool name = isValidData(data);
cout<<name;
}
bool isValidData( char data[60] )
{
int i=0;
while(data[i]!='\0') {
if ( data[i]==' ' && data[i]=='.' && data[i]=='!'){
if ( data[i+1]==' ' && data[i+1]=='.' && data[i+1]=='!')
return false;
}
i++;
}
return true;
}
Your code fails because no character can simultaneously be equal to ,, !, and .
Even if you fix that, you will still flag ,! as invalid.
Test the property directly instead:
bool isValidData( char data[60] )
{
int i=0;
while(data[i]!='\0' && data[i+1]!='\0') {
if ((data[i]==' ' || data[i]=='.' || data[i]=='!') && data[i+1]==data[i]) {
return false;
}
i++;
}
return true;
}
Related
This code is supposed to convert a given postfix expression to a prefix expression,i was experimenting with the string object in c++ but I don't have enough experience to figure out the problem
I think there's an issue in the push() function
Note:I haven't used the stack header file and implemented the stack using array
here's the code
#include <bits/stdc++.h>
#include <iostream>
#define MAX 5
using namespace std;
class stack1
{
private:
int stackTop,expTop;
string stack[MAX],expression;
public:
stack1()
{
stackTop = -1;
for (int i = 0; i < MAX; i++)
{
stack[i] = " ";
}
getexp();
check(expression);
display();
}
string pop();
void push(string expr);
void display();
bool isempty();
bool isfull();
string combo(string optr1,string optr2,string opr);
void getexp();
void check(string expre);
bool isOperator(string ch);
};
//-----------Gets Expression From User------------------------------------------
void stack1::getexp()
{
cout<<"Enter the Postfix Expression"<<endl;
cin>>expression;
expTop=expression.length()-1;
}
void stack1::check(string expre)
{
string ch;
int i=0;
while(expre[i]!=(expre.length()-1))
{
ch=expre[i];
if(isOperator(ch))
{
push(combo(pop(),ch,pop()));
}
else
{
push(ch);
}
}
}
/*
-------------------------------------------------------------------
Inputs:
takes 2 values from the stack which will be operands
either as single characters or whole strings,these
values will be passed as optr1 and opttr2,it will
also take operators such as +,-,* etc.. as char.
these will be passed in place of opr.
working:
combines all the passed values into a single string
into the following format
( optr1 opr optr2 )
and finaly returns this string
----------------------------------------------------------------------
*/
string stack1::combo(string optr1, string optr2, string opr)
{
string expr;
expr="("+optr1+opr+optr2+")";
return expr;
}
/*
------------------------------------------------------------------------
Working:
pops the top value from the stack
and returns it.
decrements the top pointer
and initializes the poped element to " "
-------------------------------------------------------------------------
*/
string stack1 ::pop()
{
string x;
if (isempty())
{
cout << endl
<< "The stack1 is empty" << endl;
}
x=stack [stackTop];
stack [stackTop] = " ";
stackTop--;
return x;
}
void stack1 ::push(string expr)
{
stackTop++;
stack [stackTop] = expr;
}
bool stack1 ::isempty()
{
if (stackTop == -1)
return true;
else
return false;
}
bool stack1 ::isfull()
{
if (stackTop == MAX - 1)
return true;
else
return false;
}
bool stack1::isOperator(string ch)
{
if (ch[0] == '*' || ch[0] == '/' || ch[0] == '+' || ch[0] == '-' || ch[0] == '^')
return true;
else return false;
}
void stack1::display()
{
cout<<"Infix:\t"<<stack[0]<<endl;
}
int main()
{
stack1 obj;
return 0;
}
Besided the obvious hard bug with #include <bits/stdc++.h> which is not part of C++ (and does not even compile on my machine), you have 2 semantic bugs in your code, which lead to a problem.
Additionally you have a design problem leading to an only partially solution.
And, maybe a misunderstanding of the terms and meaning of "string" and "character"
Example: The string "hello" consists of 5 characters: 'h', 'e', 'l', 'l', 'o'
If you use a std::string and initialize it with "hello" (which is of type const char[6]), the the constructor of the std::string will convert your character array to a std::string, containing the following characters at indices:
index character
0 'h'
1 'e'
2 'l'
3 'l'
4 'o'
5 '\0'
In your "check" function in line while(expre[i]!=(expre.length()-1)) you access expre[i] which is a character (for example an 'a') and compare it to the length of the std::string "expre". This can of course not work.
The while loop will never terminate. "i" is always the same and you will push always the first character of the input string onto the stack, unti it is full and you get an exception. You should add an overflow-check in your push function.
Additionally, you use a wrong parameter sequence in/with your "combo" function.
If you modify the while loop like the below, then at least this part will work.
string ch;
int i = 0;
//while (expre[i] != (expre.length() - 1))
while (i != (expre.length()))
{
ch = expre[i];
if (isOperator(ch))
{
push(combo(pop(), pop(),ch));
}
else
{
push(ch);
}
++i;
}
Now you can successfully convert "abcd+^" to "(a^(b(c+d)))".
But still, it will not work fully.
Additionally:
You should use your constructor only to initialize your class.
Please use characters where appropriate and not full std::strings
The whole design needs to be reworked.
Because: basically you are creating an infix and not a prefix expression.
Hence, for learning purposes look at here
So writing a palindrome with pointers and boolean. I have it working with a single word but then I began building it to work with a sentence. The problem is I am unsure how to keep the new modified sentence after making it lowercase and getting rid of the spaces for it to return whether it is or isn't a palindrome. It keeps returning the palindrome as false and when I went to check why I see that the program ignores the modification and kept the original string. I can't use "&" on the parameter as I tested it out. Any hints or takes on what I can do to keep the new modified string?
int main()
{
userInput();
return 0;
}
void userInput()
{
char str[90];
std::cout<<"Please enter a string to check if it is a palindrome: ";
std::cin.getline(str, 90);
modifyString(str);
}
void modifyString(char *string)
{
int count = 0;
for (int i=0; i<strlen(string); i++)
{
putchar(tolower(string[i]));
}
for (int i = 0; string[i]; i++)
{
if (string[i] != ' ')
{
string[count++] = string[i];
}
}
string[count] = '\0';
std::cout<<string<<std::endl;
results(string);
}
bool checkPalindrome(char *string)
{
char *begin;
char *end;
begin = string;
end = (string + strlen(string)-1);
while(begin != end)
{
if ((*begin) == (*end))
{
begin ++;
end--;
}
else
{
return false;
}
}
return true;
}
void results(char *string)
{
bool isItPalindrome;
isItPalindrome = checkPalindrome(string);
if( isItPalindrome == true)
{
std::cout<<"\nCongrats, the string is a palindrome!";
}
else
{
std::cout<<"\nThis string is not a palindrome.";
}
}
For starters this definition of main
int main()
{
userInput();
return 0;
}
does not make a sense. According to the function name main the function should perform the main task that is to output whether the entered sentence is a palindrome or not.
This for loop
for (int i=0; i<strlen(string); i++)
{
putchar(tolower(string[i]));
}
does nothing useful. It just outputs the string in the lower case.
This statement
end = (string + strlen(string)-1);
can invoke undefined behavior if an empty string was passed.
This while loop
while(begin != end)
{
if ((*begin) == (*end))
{
begin ++;
end--;
}
else
{
return false;
}
}
also can invoke undefined behavior for a string containing an even number ofo characters because after this if statement
if ((*begin) == (*end))
{
begin ++;
end--;
}
if the two adjacent characters are equal then begin after incrementing will be greater than end after its decrementing. And as a result the loop will continue its iteration.
In general the approach when the original string is changed is just a bad approach.
Your program has too many functions. It is enough to write one function that will determine whether the passed string is a palindrome or not.
Here is a demonstrative program.
#include <iostream>
#include <cstring>
#include <cctype>
bool checkPalindrome( const char *s )
{
const char *t = s + std::strlen( s );
do
{
while ( s != t && std::isspace( ( unsigned char )*s ) ) ++ s;
while ( s != t && std::isspace( ( unsigned char )*--t ) );
} while ( s != t &&
std::tolower( ( unsigned char )*s ) == tolower( ( unsigned char ) *t ) &&
++s != t );
return s == t;
}
int main()
{
const size_t N = 100;
char s[N] = "";
std::cout << "Please enter a string to check if it is a palindrome: ";
std::cin.getline( s, N );
std::cout << '\n';
if ( checkPalindrome( s ) )
{
std::cout << "Congrats, the string is a palindrome!\n";
}
else
{
std::cout << "This string is not a palindrome.\n";
}
return 0;
}
Its output might look like
Please enter a string to check if it is a palindrome: 1 23 456 6 54 321
Congrats, the string is a palindrome!
Okay, I solved it!
As one of the users on here brought up a point that my lowercase did not modify the string and only prints it out. I try my best to solve the problem and I think I found the solution and everything works perfectly fine. comment back to debug it if you like to see how it looks but what I did was create a for loop again for the lower case but made another pointer with it. here how it looks.
for (char *pt = string; *pt != '\0'; ++pt)
{
*pt = std::tolower(*pt);
++pt;
}
Now that definitely changes the string into a lower case and keeps it as a lower case.
so now the modified function looks like this and ready to take any sentence palindrome you give it. Example: A nUt fOr a jAr of tUNa. We make this all lowercase and take out space and boom palindrome and return true.
void modifyString(char *string)
{
int count = 0;
for (char *pt = string; *pt != '\0'; ++pt)
{
*pt = std::tolower(*pt);
++pt;
}
for (int i = 0; string[i]; i++)
{
if (string[i] != ' ')
{
string[count++] = string[i];
}
}
string[count] = '\0';
//take out the forward slash below to see how it looks after being modified
// std::cout<<std::endl<<string<<std::endl;
results(string);
}
I have to validate my data "123-AB-12345" as correct using character array. I set char array size to 13 including '\0'. The function must return false if the condition is not satisfied. ALL I done is that the program validates these 12 chracters but IT DOESN'T RETURN FALSE WHEN I PASS MORE VALUES like as "123-AB-123456789" and it is returning true. My program is follwing:
#include<iostream>
using namespace std;
bool isValidBookId(char bookId[13]);
int main()
{
char book[13];
cin.getline(book,13);
bool id = isValidBookId(book);
cout<<id;
}
bool isValidBookId( char bookId[13] ) {
/* Valid: 098-EN-98712 */
if ( bookId[12] != '\0' )
return false;
if ( bookId[3] != '-' )
return false;
if ( bookId[6] != '-' )
return false;
for ( int i = 0; i < 3; i++ ) {
if ( bookId[i] < '0' || bookId[i] > '9' ) {
return false;
}
}
for ( int i = 4; i < 6; i++ ) {
if ( bookId[i] < 'A' || bookId[i] > 'Z' ) {
return false;
}
}
for ( int i = 7; i < 12 || bookId[12]!='\0'; i++ ) {
if(bookId[13]!='\0'){
return false;
}
if ( bookId[i] < '0' || bookId[i] > '9' ) {
return false;
}
}
return true;
}
I don't know why this condition is not working.
if ( bookId[12] != '\0' )
return false;
Looking at your code, the only explanation is that the last character of your array is null. Try specifying a delimiter character like this:
cin.getline(book, 13, '\n');
I'd refer to this link:
"A null character ('\0') is automatically appended to the written sequence if n is greater than zero, even if an empty string is extracted."
Your issue is in your input function:
You only read up to 12 characters. So you cannot have more than 12 characters.
You might use std::string
bool isValidBookId(const std::string&s) {
static const std::regex r{R"(^\d{3}-[A-Z]{2}-\d{5}$)"};
return std::regex_match(std::begin(s), std::end(s), r);
}
int main()
{
std::string s;
while (std::getline(std::cin, s))
{
std::cout << s << ": " << isValidBookId(s) << std::endl;
}
}
Demo
Or bigger buffer:
bool isValidBookId(const char (&s)[14]) {
static const std::regex r{R"(^\d{3}-[A-Z]{2}-\d{5}\0$)"};
return std::regex_match(std::begin(s), std::end(s) - 1, r);
}
int main()
{
char s[14];
while (true)
{
bool b = !!std::cin.getline(s, 14);
if (s[0] == '\0') break;
std::cout << " " << s << ": " << isValidBookId(s) << std::endl;
if (!b) {
std::cin.clear();
std::cin.ignore(255, '\n');
}
}
}
Demo
All conditions are correct. Your problem is created initially when entering data.
cin.getline(book,13);
The 'getline' method accepts any number of characters (of course within reason), but allocates space only for the first 12 characters and the 13th will always be only '\ 0'. If you want to write more characters, let me enter more characters.
The correct option is:
bool isValidBookId(char bookId[100]); // now there is a restriction of not 13 characters, but 100
int main()
{
char book[100]; // now there is a restriction of not 13 characters, but 100
cin.getline(book,100); // now there is a restriction of not 13 characters, but 100
}
bool isValidBookId( char bookId[100] ) // now there is a restriction of not 13 characters, but 100
{...}
As pointed above,
cin.getline(book,13) wont save more than 12 characters in your array.
Instead replace your code with :
char book[100]; // To save upto 99 characters
cin.getline(book,100);
And change
isValidBookId(char bookId[13])
to
isValidBookId( char bookId[100] )
and remove all the checks of
bookId[12]!='\0' inside this isValidBookId function, as there can be any character at 12th index.
I am creating a c++ program to validate book ID using function in c++. The program must return 1 if the input is valid and 0 if the input is invalid. INPUT Pattern: "123-AB-12345" This will be considered as a valid input. The valid input is: (a) Total characters must be 12 (b) First three characters must be integers from 1 to 9 each. (c) 4th and 7th characters must be hiphen "-". (d) Last 5 characters must be integers from 1 to 9 each.
I tried the following way but I am not getting the desired answer. Need help plz
#include<iostream>
using namespace std;
bool isValidBookId(char bookId[13]);
int main()
{
char book[13];
cin.getline(book,12);
bool id = isValidBookId(book);
cout<<id;
}
bool isValidBookId(char bookId[13])
{
int i;
bool check1,check2,check3,check4,check5,check6;
check1=check2=check3=check4=check5=true;
if(bookId[12]=='\0'){
check1=true;
}
if(bookId[3]=='-')
{
check2=true;
}
if(bookId[6]=='-')
{
check3=true;
}
for(i=0; i<3;i++){
if(bookId[i]>=0 || bookId[i]<=9)
{
check4=true;
}
}
if(bookId[i]>= 'A' || bookId[i]<= 'Z')
{
check5=true;
}
for(i=7; i<12; i++)
{
if(bookId[i]>=0 || bookId[i]<=9)
{
check6=true;
}
}
if(check1==true && check2==true && check3==true && check4==true && check5==true && check6==true)
{
return true;
}
else
{
return false;
}
}
There's a few errors that you have in your code.
First, you initialize all your checks to true, and never set anything to false, so the answer will always be true. Realistically, you want to initialize them all to false, and change to true when all the conditions are met, or assume true, and set to false when the condition is not met.
Second, your check for the values 0-9 is incorrect. You cannot compare bookId[i] to 0, you want to compare it to the character '0'. Also note that the question you have also says 1-9 not 0-9
Third, your check for A-Z is incorrect (note, this issue also applies to 0-9). You're code basically says is bookId[i] greater than or equal to 'A' OR less than or equal to Z, which is always going to be true.
I've written your code below:
bool isValidBookId( char bookId[13] ) {
if ( bookId[12] != '\0' )
return false;
if ( bookId[3] != '-' )
return false;
if ( bookId[6] != '-' )
return false;
for ( int i = 0; i < 3; i++ ) {
if ( bookId[i] < '1' || bookId[i] > '9' ) {
return false;
}
}
for ( int i = 4; i < 6; i++ ) {
if ( bookId[i] < 'A' || bookId[i] > 'Z' ) {
return false;
}
}
for ( int i = 7; i < 12; i++ ) {
if ( bookId[i] < '1' || bookId[i] > '9' ) {
return false;
}
}
return true;
}
This method doesn't require any Boolean variables. Instead, I assume true (the last return statement) and instead try to prove false. As soon as something is false, you can return without doing any other checks.
Since the given code is in C-Style format, I would like to present 2 additional solutions in C++. I think the task is anyway to think about patterns and how these could be detected.
In my first solutions I just added more C++ elements. The 2nd solution should be the correct on.
Please see:
#include <iostream>
#include <regex>
#include <string>
#include <cctype>
#include <vector>
bool isValidBookId1(const std::string& bookId) {
// Lambda to detect hyphen
auto ishyphen = [](int i){ return static_cast<int>(i == '-');};
// First check size of given string
bool result{(bookId.size() == 12)};
// Define the position of the types
std::vector<size_t> digitIndex{0,1,2,7,8,9,10,11};
std::vector<size_t> letterIndex{4,5};
std::vector<size_t> hyphenIndex{3,6};
// Check types
if (result) for (size_t index : digitIndex) result = result && std::isdigit(bookId[index]);
if (result) for (size_t index : letterIndex) result = result && std::isupper(bookId[index]);
if (result) for (size_t index : hyphenIndex) result = result && ishyphen(bookId[index]);
// Return resulting value
return result;
}
bool isValidBookId2(const std::string& bookId) {
// Define pattern as a regex
std::regex re{R"(\d{3}-[A-Z]{2}-\d{5})"};
// Check, if the book id matches the pattern
return std::regex_match(bookId, re);
}
int main()
{
// Get input from user
if (std::string line{}; std::getline(std::cin, line)) {
std::cout << "Check for valid Book input 1: " << isValidBookId1(line) << "\n";
std::cout << "Check for valid Book input 2: " << isValidBookId2(line) << "\n";
}
return 0;
}
Can someone please point out the reason for the segmentation fault in my code. I am trying to convert an arithmetic expression with precedence decided by '()' into postfix form and then solve the expression.
#include<iostream>
#include<string>
#include<stack>
using namespace std;
string post(string exp)
{
cout<<"reached post";
stack<char> s2;
string new_exp="";
int length=exp.length();
for(int i=0; i<length; i++)
{
if(exp[i]=='(')
{
s2.push(exp[i]);
}
else if(exp[i]=='+'|| exp[i]=='-' || exp[i]=='*' || exp[i]=='/')
{
new_exp+=' ';
s2.push(exp[i]);
}
else if(exp[i]>='0'&& exp[i]<='9')
{
new_exp+=exp[i];
}
else if(exp[i]==')')
{
new_exp+=' ';
new_exp+=s2.top();
s2.pop();
s2.pop();
}
}
if(!s2.empty())
{
while(!s2.empty())
{
new_exp+=' ';
new_exp+=s2.top();
s2.pop();
}
}
return(new_exp);
}
int operation(char op, char op1, char op2)
{
if(op == '+') return(op1+op2);
else if(op=='-') return(op1-op2);
else if(op=='*') return(op1*op2);
else if(op=='/') return(op1/op2);
}
int solve(string expression)
{
cout<<"\nreached solve";
string postfix=post(expression);
stack<char> s;
int res;
int length=postfix.length();
for(int i=0; i<length; i++)
{
if(postfix[i]==' ')
{
continue;
}
else if(postfix[i]=='+'|| postfix[i]=='-' || postfix[i]=='*' || postfix[i]=='/')
{
char op2=s.top();
s.pop();
char op1=s.top();
s.pop();
res=operation(postfix[i],op1,op2);
s.push(res);
}
else if(postfix[i]>='0' && postfix[i]<=9)
{
int operand=0;
while(postfix[i]!=' ' || i!=length)
{
operand=(operand*10)+(postfix[i]-'0');
i++;
}
i--;
s.push(operand);
}
}
return(res);
}
int main(void)
{
string exp;
int result;
cout<<"Enter expression: ";
getline(cin,exp);
result=solve(exp);
cout<<"\nResult= "<<result;
return 0;
}
I get the following error message:
cav#cav-VirtualBox:~/src/cpp$ ./infix_postfix
Enter expression: 10+3
Segmentation fault (core dumped)
I can see at least two mistakes. First,
else if(postfix[i]>='0' && postfix[i]<=9)
You need to compare character '9', not integer 9 as you have a string here. It should be:
else if(postfix[i]>='0' && postfix[i]<='9')
^ ^
Second problem is here:
while(postfix[i]!=' ' || i!=length)
You meant and operation && here, not or ||. When it's a || it is basically true for all characters except i runs out of the length. Also i != length should be tested before postfix[i] != ' ' since when i == length postfix[i] will be out of bound. This line should be:
while(i!=length && postfix[i]!=' ')
Due to these two mistakes you are not pushing values to your stack correctly, getting erronous values at different times which is leading to segmentation fault.