I need to convert characters from a string into int's then place them into a vector. I started by making a new string of the numbers without the spaces. I then want to iterate through the numbers in the result string and convert to int, then push into a vector. I am having issues with the negative numbers not converting to the right values. I commented out the vector part because I realized the issue is before that, the wrong values are going into the vector.
#include <iostream>
#include <sstream>
#include <vector>
using namespace std;
int main() {
string result = "";
string str = "8 3 -5 42 -1 0 0 -9 4 7 4 -4";
for(char c : str) {
if(c == ' ') {
continue;
}
else {
result += c;
}
}
cout << "result: " << result;
vector<int> lst;
//for(int x = 0; x < result.length(); x++) {
//lst.push_back(result[x] - '0');
//}
//testing the values being converted
int x = result[2] - '0';
cout << "\n" << x;
}
For example,
int x = result[0] - '0';
cout << "\n" << x;
gives me 8, which is the right conversion of the first number in the string.
but,
int x = result[2] - '0';
cout << "\n" << x;
gives me -3, which is not the -5 I am looking for. I am stuck on this and I cannot figure out why the negative numbers are not properly converting, or where the -3 is even coming from. Any help is appreciated, thank you.
Your input is: "8 3 -5 42 -1 0 0 -9 4 7 4 -4"
You put non-space characters into the result array, so:
result[0]->'8'
result[1]->'3'
result[2]->'-'
result[3]->'5'
So result[2] is - which has an ASCII code of 45. The zero digit has an ASCII code of 48. So result[2] - '0' is 45 minus 48 or -3.
You don't say why you expect -5. What character do you think is five less than the digit zero?
Related
i am a novice to C++ , I was trying to write this program for adding two very large numbers using strings but the program is not working correctly and I can't get what's wrong with it , please help me with this.
#include<iostream>
#include<stack>
#include<string>
using namespace std;
int main() {
stack <char> a1;
stack<char> a2;
stack<int> result;
stack<int> temp;
int carry = 0;
string num1;
string num2;
cout << "Enter first number (both numbers should have equal digits)" << endl;
getline(cin, num1);
cout << "Enter second number" << endl;
getline(cin, num2);
for (int i = num1.size()-1; i >= 0; i--) {
a1.push(num1[i]);
a2.push(num2[i]);
}
while (!a1.empty() && !a2.empty()) {
int element = (int)a1.top() + (int)a2.top() + carry;
cout << element;
if (element > 10) {
element %= 10;
carry = 1;
}
result.push(element);
cout << result.top() << endl;
a1.pop();
a2.pop();
}
string abc;
while (!result.empty()) {
temp.push(result.top());
result.pop();
abc += temp.top();
}
cout << abc;
}
I know i have definitely made a logical mistake , but i can't get it , can anyone please guide me?
the following is the output am getting
I was thinking, why stacks should be used. My guess is that you did this, because the numbers must be processed from right to left.
Additionally, you have obiously a challenge with strings with a different length.
But both problems can be solved easily. Let us start with the different length strings.
If 2 strings have a different length, we can pad (fill in) the shorter string with leading `0's. How many leading '0s' do we need to add? Right, the delta of the lengths.
And for inserting characters in a string at a certain position, we have the function insert.
So, the code for that will look like this:
if (numberAsString1.length() < numberAsString2.length())
numberAsString1.insert(0, numberAsString2.length() - numberAsString2.length(), '0');
else
numberAsString2.insert(0, numberAsString1.length() - numberAsString2.length(), '0');
This is rather straightforward.
The result will always be 2 strings with equal length. With entering "1234" and "9", we will get: "1234" and "0009".
This makes the next task easier.
Now that we have 2 equal length strings, we can "add", like we learned in school.
We go from right to left, by starting with the highest possible index of a character in the string. This is always length-1.
For calculating the sum, we need first to subtract the ASCII code for '0' from the characters in the string, because the string contains not integer numbers, but characters. For example "123" consists of '1', '2', '3' and not of 1,2,3.
Suming up is then easy: digit + digit + carry.
The resulting digit is always the sum % 10. And the next carry is always sum / 10. Example 1: 3+5=8 8%10=8 8/10=0. Example 2: 9+8=17 17%10=7 17/10=1.
So, also this is rather simple.
After we worked on all digits of the strings, there maybe still a set carry. This we will then add to the string.
Adding digits will be done in any case using the instert function. Because we want to insert digits on the left side of the resulting string.
So, with working from right to left, using correct indices and the insert function, we do not have the need for a stack.
With a lot of input checking, the whole function would look like this:
#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>
int main() {
// Give instruction to user
std::cout << "\nPlease enter 2 positive interger numbers:\n";
// Here we will store the user input
std::string numberAsString1{}, numberAsString2{};
// Get strings from user and check, if that worked
if (std::cin >> numberAsString1 >> numberAsString2) {
// Check if all characters in string 1 are digits
if (std::all_of(numberAsString1.begin(), numberAsString1.end(), std::isdigit)) {
// Check if all characters in string 2 are digits
if (std::all_of(numberAsString2.begin(), numberAsString2.end(), std::isdigit)) {
// ---------------------------------------------------------------------------------
// Here we will store the calculated result
std::string result{};
// Temporary helpers
unsigned int carry{};
// ---------------------------------------------------------------------------------
// Make strings equal length. Pad with leading '0' s
if (numberAsString1.length() < numberAsString2.length())
numberAsString1.insert(0, numberAsString2.length() - numberAsString2.length(), '0');
else
numberAsString2.insert(0, numberAsString1.length() - numberAsString2.length(), '0');
// ---------------------------------------------------------------------------------
// Iterate over all digits from right to left
for (int i = numberAsString1.length()-1; i >= 0; --i) {
// Calculate the sum
const int sum = numberAsString1[i]-'0' + numberAsString2[i] - '0' + carry;
// Get the carry bit in case of overflow
carry = sum / 10;
// Save the resulting digit
result.insert(0, 1, sum % 10 + '0');
}
// handle last carry bit
if (carry) result.insert(0, 1, '1');
// ---------------------------------------------------------------------------------
// Show result
std::cout << "\n\nSum: " << result << '\n';
}
else std::cerr << "\n\nError: number 1 contains illegal characters\n";
}
else std::cerr << "\n\nError: number 2 contains illegal characters\n";
}
else std::cerr << "\n\nError: Problem with input\n";
return 0;
}
This question already has answers here:
C++ handling very large integers
(15 answers)
Closed 3 years ago.
I am supposed to get two big integer numbers (up to 600 digits) from console screen and write the result on the console again.
I defined two variables of type std::string to store two big integer numbers .I take their values from the user. To take the sum of that two numbers, I defined two vectors to store the digits of that two strings of numbers .
Here is the problem, when I try to loop through the vector to print the digits that I took from strings of numbers I get the following result .The Ascii values of the digits are printed on The Console.
Could anyone tell me how to fix this problem please.
Note: The code is still not complete .
For the first string I took the numbers 9 8 7 6 5 4 3 2 1 from the user , on the console window I got the following result.
[0]57
[1]56
[2]55
[3]54
[4]53
[5]52
[6]51
[7]50
[8]49
#include <iostream>
#include <sstream>
#include <vector>
#include <algorithm>
std::string Sum_Of_Two_Long_Integers()
{
std::string First_String ;
std::string Second_String ;
std::string Result_String ;
std::cout << "Please enter the first number: " ;
std::getline(std::cin, First_String);
std::cout << "Please enter the second number: " ;
std::getline(std::cin, Second_String);
std::vector <int> First_String_Vector (First_String.length()) ;
std::vector <int> Second_String_Vector (Second_String.length()) ;
for(int Counter = 0 ; Counter < First_String_Vector.size() ; ++ Counter)
{
First_String_Vector[Counter] = First_String[Counter] ;
Second_String_Vector[Counter] = Second_String[Counter] ;
std::cout << "[" << Counter << "]" << First_String_Vector[Counter] << std::endl ;
}
return Result_String ;
}
int main()
{
std::string Result_String = Sum_Of_Two_Long_Integers() ;
std::cout << "Result = " << Result_String << std::endl ;
return 0 ;
}
First_String_Vector[Counter] = First_String[Counter] ;
Second_String_Vector[Counter] = Second_String[Counter] ;
The digits are stored as ASCII in you string, you should convert to integer before placing them into the vector.
This would do the trick:
First_String_Vector[Counter] = First_String[Counter] - '0';
Second_String_Vector[Counter] = Second_String[Counter] - '0';
I would also add a check for valid input before populating your vectors to make sure that you only read digits:
if(First_String[Counter] < '0' || First_String[Counter] > '9' ||
Second_String[Counter] < '0' || Second_String[Counter] > '9')
{
std::cout << "Invalid input\n";
return "":// Or better throw an exception
}
EDIT: '6' isn't equal to 6. The first one is a char, its value is ASCII for character '6', and the second is the integer 6.
ASCII is an encoding. Characters are mapped to some numbers. Value for '0' is 48, '1' is 49, ..., '9' is 57
To be even more precise C++ does not guarantee to use ASCII encoding (though I don't know of an implementation that does not use it), but it does guarantee that '0'...'9' have contiguous integer values. So '6' - '0' will give us integer 6.
I have an array ( char location[2]; ) This needs to receive two values from the user. The first is a letter the other a number, in that order. This is used to select a location in a 9 x 9 grid.
The grid appears
A B C D E F G H I
1
2
3
4
5
6
7
8
9
When I try to store the second value as an int, The method I would think would work is being set to -48.
int row = location[1] - 48;
48 is the ASCII value of '1'. Shouldn't this have created an int with the value of one less than whatever number was input by the user? '2' (aka 49) - 48 = 1? It always comes out as -48 no matter what the input is.
My full function:
#include <iostream>
using namespace std;
void getLocation(int &column, int &row)
{
int row = 0;
int column = 0;
char location[2];
cout << "location: ";
cin.getline(location,2);
cin.ignore();
cin.clear();
switch (location[0])
{
case 'A':
cout << "case A\n";
column = 0;
break;
case 'B':
cout << "case B\n";
column = 1;
break;
case 'C':
cout << "case C\n";
column = 1;
break;
}
row = location[1] - 48;
cout << "column: "
<< column
<< " row: "
<< row
<< "\n";
}
location[1] - 48 will always be -48 if positive-length string is given because terminating null-character will be stored there. Allocate enough length to store the input. You are using C++, so using std::string is better to store strings than using arrays of char.
cin.getline(location,2) does not behave in the way you expect.
It writes a nul-terminated string to location i.e. location[0] is read from cin, and location[1] receives a character with value of 0 (numeric zero, not '0').
0 - 48 always produces a result of -48 as an int.
Note, also, that '1' is not guaranteed to have a value of 48. '0' does in ASCII and compatible character sets. Other character sets will give different values.
You would be better off using std::string - that eliminates the need to worry about arrays of char and nul termination.
The size of the stream for cin.getline needs space for a null terminator. Therefore, increase the size of the stream buffer and terminate input on the carriage return:
cin.getline(location, 3, '\r');
I am writing a code where I take user user text input, convert it to binary, store each binary character in an element in an array and then print A or T for 0 and G or C for 1 at random. But the ATGC seem to not follow this rule and they come at random for every digit; 0 and 1. So If the binary is 0010101 I need output as ATGACTG. Also when I store the binary in an int variable, the zero in front of it vanishes. Is there a way to keep it?
#include <iostream>
#include <cstdlib>
#include <bitset>
#include <string>
#include <ctime>
int main()
{
using namespace std;
int p, i=0, a[100000];
int s;
string myString;
int binary;
cout << "Type your text: ";
std::getline (std::cin,myString);
for (std::size_t k=0; k < myString.size(); ++k)
{
std::bitset<8> y(myString[k]);
std::string dna = y.to_string();
binary = atoi(dna.c_str());
cout << binary;
while (binary != 0)
{
a[i] = binary % 10;
binary = binary / 10;
i++;
}
}
std::cout << std::endl;
srand(time(0));
for (int j = (i-1); j>-1; j--)
{
if (a[j] == 0)
{
p = rand() %2;
if (p==0)
cout<< "A";
else
cout<< "T";
}
if (a[j] == 1)
{
s = rand() %2;
if (s == 0)
cout<< "G";
else
cout<< "C";
}
else
{
cout << "";
}
}
}
I don't know why exactly you wrote so much wrong code, but I've managed to extract (and change) the code that actually does the job.
#include <iostream>
#include <string>
#include <bitset>
#include <ctime>
int main()
{
int i = 0, a[8];
std::string myString;
std::cout << "Type your text: " << std::endl;
std::getline(std::cin, myString);
for(auto x : std::bitset<8>(myString).to_string())
a[i++] = x == '1';
std::cout << std::endl;
srand(time(0));
for(int j = 0; j < i; ++j)
if(a[j] == 0)
std::cout << (rand() % 2 ? "T" : "A");
else if(a[j] == 1)
std::cout << (rand() % 2 ? "C" : "G");
std::cout << std::endl;
}
And here's neater version of main:
int main()
{
std::vector<int> a; // using std::vector
std::bitset<8> bs;
std::cout << "Type your text: " << std::endl;
std::cin >> bs; // std::bitset can be read from stream via operator>>
for(auto x : bs.to_string())
a.push_back(x == '1');
std::cout << std::endl;
srand(time(0));
for(auto x : a)
if(x == 0)
std::cout << (rand() % 2 ? "T" : "A");
else if(x == 1)
std::cout << (rand() % 2 ? "C" : "G");
std::cout << std::endl;
}
Just ask if you want an explanation on some specific part.
I told you not to convert the string to an integer. You didn't listen. This is why leading 0 vanishes.
Your output seams to be completely random because you reverse the order of characters in the sequence when reading the information from a.
Here is how I'd solve your problem: run online
#include <iostream>
#include <string>
#include <bitset>
#include <ctime>
#include <cstdlib>
int main()
{
std::cout << "Type your text: " << std::endl;
std::string in_str;
std::getline(std::cin, in_str);
std::string binary_str;
for(int i = 0; i < in_str.size(); ++i)
{
char c = in_str.at(i);
binary_str.append(std::bitset<8>(c).to_string());
}
std::cout << binary_str << std::endl;
srand(time(0));
for(int i = 0; i < binary_str.size(); ++i)
{
char c = binary_str.at(i);
if(c == '0')
std::cout << (rand() % 2 ? "T" : "A");
else
std::cout << (rand() % 2 ? "C" : "G");
}
std::cout << std::endl;
}
If you have any questions, ask me in the comments.
Edit: the OP asked me to explain all mistakes in his program.
Where did all those zeros gone?
To answer this question I'll have to explain all things your program does line-by-line.
Here you convert a symbol to a bitset:
std::bitset<8> y(myString[k])
For example: if k is 'a', then the y would be 01100001.
Here you convert the bitset to a string:
std::string dna = y.to_string();
In our example the dna would be "01100001".
Here you convert the string to an integer:
binary = atoi(dna.c_str());
A very simplified version of what atoi does:
binary = 0;
for(int i = 0; i < dna.size(); ++i)
binary = binary * 10 + (dna.at(i) - '0')
In our example the binary would be 1100001.
Note: that's NOT where you loose zeros. At this point you are still able to extract them because you know that you need to extract 8 digits. So you can append leading zeros to up it's length to 8.
The next line is where you actually loose zeros the first time because cout doesn't know that you want to print 8 digits.
cout << binary;
In our example it would print 1100001.
And here you loose zeros again because you stop extracting digits as soon as binary == 0 even if you extracted less than 8 digits. Also note that you are actually reversing what the function atoi just did with the only difference that you don't get your leading zeros back and the reverse order of bits (see the next paragraph):
while (binary != 0)
{
a[i] = binary % 10;
binary = binary / 10;
i++;
}
Why the output is "random"?
Here you are iterating through myString in the standard order
for (std::size_t k=0; k < myString.size(); ++k)
e.g. if myString is "abc" than
in the first iteration myString[k] would be 'a'
in the second iteration myString[k] would be 'b'
in the third iteration myString[k] would be 'c':
But in this loop you extract digits in reverse order:
while (binary != 0)
{
a[i] = binary % 10;
binary = binary / 10;
i++;
}
eg if binary is 1100001
in the 1st iteration you extract 1 and binary becomes 110000
in the 2nd iteration you extract 0 and binary becomes 11000
in the 3rd iteration you extract 0 and binary becomes 1100
in the 4th iteration you extract 0 and binary becomes 110
in the 5th iteration you extract 0 and binary becomes 11
in the 6th iteration you extract 1 and binary becomes 1
in the 7th iteration you extract 1 and binary becomes 0
Now you end up with an array where bits inside a character code are reversed, but different characters are stored in the array in the normal order.
e.g. If the input string was "abc", then a would become:
1,0,0,0,0,1,1, 0,1,0,0,0,1,1, 1,1,0,0,0,1,1
reversed 'a' reversed 'b' reversed 'c'
If you iterate through a in normal order, the order of bits inside character codes would be reversed. If you iterate through a in reverse order, you get the reversed order of characters.
As a rule of thumb: don't program by guessing, program by thinking.
Further reading
The Zen of Python. Most of this aphorisms are applicable to every programming language with the exception of Brainfuck
Raw C arrays are evil
I have to convert decimal numbers like 43.62 to binary. So i first wrote a basic program that converts 43 into binary. But I notice that my program prints out the binary number in reverse, so it prints 1 1 0 1 0 1 instead of 1 0 1 0 1 1. how can I fix this.
My Code:
#include <iostream>
using namespace std;
int main()
{
int number;
int remainder;
cout << "Enter a integer: ";
cin >> number;
while(number != 0)
{
remainder = number % 2;
cout << remainder << " ";
number /= 2;
}
int pause;
cin >> pause;
return 0;
}
Instead of sending each digit to cout, send them to an array. Then read the array out in reverse order. Or push them onto a stack, and then pop them back off the stack. Or...
Something of a sledgehammer to crack a nut, but here's a solution based on a recursive approach:
#include <iostream>
using namespace std;
void OutputDigit(int number)
{
if (number>0)
{
OutputDigit(number /= 2);
cout << number % 2 << " ";
}
}
int main()
{
OutputDigit(43);
return 0;
}
You can get the same output as you had before by simply moving the cout one line up!
Look at vector and think about how it could be useful to save the remainders instead of printing them right away.
Notice that you don't have to put things at the end of the vector. vector::insert lets you specify a position... could that be helpful?
Alternatively, the algorithm you created starts at the least significant digit. Is there a way to start from the most significant digit instead? If I have the number 42 (0101010), the most significant digit represents the 32s, and the 0 ahead of it represents the 64s. What happens if I subtract 32 from 42?
It would be easier to store the results and then print them backwards. Using recursion is also another possibility to do just that.
Most significant bit first:
const unsigned int BITS_PER_INT = CHAR_BIT * sizeof(int);
char bit_char = '0';
for (int i = BITS_PER_INT - 1;
i > 0;
--i)
{
bit_char = (value & (1 << i)) ? '1' : '0';
cout << bit_char << ' ';
}
cout << '\n';
cout.flush();
To print least significant bit first, change the direction of the for loop.
In C++, you can also use a bitset container to do this,
#include <bitset>
int i = 43;
std::bitset<sizeof(int)*CHAR_BIT> bin(i);
Just use string functions
string s ;
while(number != 0)
{
remainder = number % 2;
string c = remainder ? "1": "0";
s.insert(s.begin(),c.begin(),c.end());
number /= 2;
}
When you do such conversion by holding on to the remainder, the result will always be reverted. As suggested use bitwise &:
unsigned char bit = 0x80; // start from most significant bit
int number = 43;
while(bit)
{
if( bit & number ) // check if bit is on or off in your number
{
cout << "1";
}
else
{
cout << "0";
}
bit = bit >>1; // move to next bit
}
This example will start going through all your 8 bits of the number and check if the bit is on or off and print that accordingly.
Best option - Use C++ stringstream for formatting I/O
// Add the following headers
#include <sstream>
#include <algorithm>
// your function
stringstream ss;
// Use ss in your code instead of cout
string myString = ss.str();
std::reverse(myString.begin(),myString.end());
cout << myString;