I had a problem while trying to equal one string to another, I get this error "Error reading characters of string." in Visual Studio 2015, in the line that i am doing this "student_name=otherStudent.student_name;" and I just don't get it.
could you please help me?
Student& Student::operator=(const Student &otherStudent) {
if (this != &otherStudent) // Avoid self assignment
{
student_name=otherStudent.student_name;
for (int i = 0; i < grades_size; i++) {
grades[i] = otherStudent.grades[i];
subjet_names[i] = otherStudent.subjet_names[i];
}
average_grade = otherStudent.average_grade;
}
return *this;
}
Here is the definition of the class if it helps:
#include <iostream>
#include <string>
using namespace std;
#define grades_size 6
class Student {
private:
string student_name;
float grades[grades_size];
string subjet_names[grades_size];
float average_grade;
public:
//Constructor
Student();
Student(string name);
//Print status of Student
void printStudent();
//Operator Overloads
Student & operator=(const Student & otherStudent);
};
Related
I am trying to code the number of occurences of 'e' in a particular string but it is giving me error while defining the function as it says string is not defined in this scope and occurence_e(which is my user-def function) to be not declared in this scope as well.
Following is the code:
#include<iostream>
#include<string.h>
void occurence_e(string);
using namespace std;
int main(){
string input;
cout<<"Enter any name"<<endl;
cin>>input;
occurence_e(input);
return 0;
}
void occurence_e(string input){
int count=0;
for (int i = 0; i < input.length(); i++)
{
if(input.at(i)=='e'){
count++;
}
}
cout<<"No. of times e comes in this name is "<<count;
}
The forward reference uses string, so move using namespace std; above it.
using namespace std;
void occurence_e(string);
I am creating a class that has two members string and int
I want to use the constructor to initialize both of these two members to use them.
#pragma once
#include <string>
#include <iostream>
using namespace std;
class donation_1
{
public:
//string name;
const char* name;
int donation_amount;
const static size_t string_size = sizeof(string);
const static size_t int_size = sizeof(int);
donation_1(char* name_1 = "Noname", int amount = 0) : name(name_1), donation_amount(amount) {};
};
int main()
{
fstream file;
file.open("donation_total1.txt", ios_base::app);
if (file.is_open())
{
donation_1("xxxx", 20).writedata(file);
donation_1("yyyy", 30).writedata(file);
donation_1("zzzz", 40).writedata(file);
donation_1("MMMM", 50).writedata(file);
donation_1("BBBB", 60).writedata(file);
file.close();
}
else
{
cout << "file couldn't be opened" << endl;
}
return 0;
}
I want to use the constructor to initialize the class variables which I will be using to update a file, however, what I am getting is this error. this error is regarding initializing the string class member.
Severity Code Description Project File Line Suppression State
Error (active) E0310 default argument of type "const char *" is incompatible with parameter of type "char *" Stream_File_Lab D:\INVSPRIVATE\C++\Projects\Stream_File_Lab\donation_1.h 17
The error message is makes it pretty clear. The variable 'name' is declared as const char* but the value being assigned to it is only char* i.e. the const-ness is missing, hence the type incompatibility error throws up.
Please, google for pointer to a const value and how to use them.
Maybe check this tutorial
I was trying to make a basic class program to practice making classes, however even though I followed a tutorial visual ++ says Person() expression must have a class type.
I don't really understand what it's saying and didn't find anything after looking it up. here is my code:
//My main program
// ConsoleApplication1.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include "Person.h"
using namespace std;
int main(){
Person person();
cout << person.getName() << "Age = " << person.getAge() << endl;
return 0;
}
//My person.cpp file
#include "stdafx.h"
#include "person.h"
Person::Person() {
name = "unknown";
age = 0;
}
string Person::getName() {
return "person's name is " + name;
}
int Person::getAge() {
return age;
}
//My person.h file
#pragma once
#include "Person.cpp"
#include <iostream>
#include <string>
using namespace std;
class Person {
private:
string name;
int age;
public:
Person();
string getName();
int getAge();
};
To expand on what #Igor Tandetnik is saying when you are creating the instance of Person you are actually declaring a function which is called person and returns a data type of Person. This function takes no parameters, hence: (). What you want to do is
int main(){
Person person;
//...
//...
}
doing it this way creates an instance of a Person called person, or in easier terms creating a Person called bob would be Person bob; and not Person bob();
In my source file when I define my object s, Visual Studios says Identifier "stack" is undefined. I'm pretty sure I've separated the headers correctly but I don't know why I'm getting this error. Also side note when I put everything together in one source file and compile it, it just exits immediately without any reason. Thanks for the help in advance.
This is the source file
// pa3.cpp : Defines the entry point for the console application.
//
#include "stack.h"
#include "stdafx.h"
#include <iostream>
#include <string>
#include <fstream>
//#include <ctype.h>
using namespace std;
int main()
{
//int count;
stack s; //assign s object to stack
string input;
cout << "Please enter the name of the input file: \n";
//cin >> input;
getline(cin, input);
ifstream file(input);
string readline;
//ifstream file(input);
while (getline(file, readline)) //take first line of file and assign to readline
{
s.push(readline); //send it off to push
s.retrieveUPPER();
//file.close();
system("pause");
}
return 0;
}
This is the stack.h file
//#pragma once
#include "stdafx.h"
#include <iostream>
#include <string>
#include <fstream>
//#include <ctype.h>
using namespace std;
class stack
{
public:
int count;
void push(string);
//void pop();
void check(string);
void retrieveUPPER();
private:
static string firstline[1];
static string diskeywords[3];
static char upperword[100];
static char lowerword[100];
static char operatorsarr[100];
static char delimitersarr[100];
};
This is the stack.cpp
#include "stack.h"
#include "stdafx.h"
#include <iostream>
string stack::firstline[1] = { 0 };
string stack::diskeywords[3];
char stack::upperword[100];
char stack::lowerword[100];
char stack::operatorsarr[100];
char stack::delimitersarr[100];
void stack::retrieveUPPER()
{
for (int i = 0; i < 100; i++)
{
cout << upperword[i] << "\n";
}
}
void stack::push(string readline)
{
firstline[0] = readline;
count++;
check(readline);
}
void stack::check(string readline)
{
int length;
char letter;
int leftperenthe = 0;
int rightperenthe = 0;
//int capital;
//int wordFOR;
//int wordBEGIN;
//char keywords[3][8] = { "FOR", "BEGIN", "END" };
char operators[] = "+-=*/;";
char delimiters[] = { ',',';' };
length = readline.length();
for (int i = 0; i < length; i++)
{
for (int j = 0; j < 5; j++)
{
letter = readline[i];
if (isupper(letter)) //if capital letter
{
upperword[i] = letter;
}
else if (islower(letter)) //if lowercase letter
{
lowerword[i] = letter;
}
else if (letter == operators[j]) //if encounters a operator
{
operatorsarr[i] = letter;
}
else if (letter == delimiters[j]) //if encounters a delimiter
{
delimitersarr[i] = letter;
}
else if (letter = ' ') //if encounters a space
{
lowerword[i] = ' ';
operatorsarr[i] = ' ';
delimitersarr[i] = ' ';
}
else if (letter = '(') //if left perenthesis
{
leftperenthe++;
}
else if (letter = ')') //if right perenthesis
{
rightperenthe++;
}
}
}
}
I also had a similar situation:
#include<iostream>
#include<stack.h>
#include<vector>
using namespace std;
int main();
std::vector<int>stickPan (std::vector<int>arr)
{
stack<int>s;
...
}
I used VScode, used mingw-w64, and added paths for * .h files to .json files, but it didn't work.
Errors are reported:
identifier "stack" is undefined.
type name is not allowed.
identifier "s" is undefined
I am trying to tokenize a database dump separated by commas. I only need to read the first word, which will tell me if this is the line I need and then tokenize the line and save each separated string in a vector.
I have had trouble keeping all of the datatypes in order. I use a method of getline:
string line;
vector<string> tokens;
// Iterate through each line of the file
while( getline( file, line ) )
{
// Here is where i want to tokenize. strtok however uses a character array and not a string.
}
The thing is, I only want to continue reading and tokenize a line if the first word is what I am after. Here is a sample of a line from the file:
example,1,200,200,220,10,550,550,550,0,100,0,-84,255
So, if I am after the string example, it goes ahead and tokenizes the rest of the line for my use and then stops reading from the file.
Should I be using strtok, stringstream or something else?
Thank you!
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
void do(ifstream& file) {
string line;
string prefix = "example,";
// Get all lines from the file
while (getline(file,line).good()) {
// Compare the beginning for your prefix
if (line.compare(0, prefix.size(), prefix) == 0) {
// Homemade tokenization
vector<string> tokens;
int oldpos = 0;
int pos;
while ((pos = line.find(',', oldpos)) != string::npos) {
tokens.push_back(line.substr(oldpos, pos-oldpos));
oldpos = pos + 1;
}
tokens.push_back(line.substr(oldpos)); // don't forget the last bit
// And here you are!
}
}
}
How do I tokenize a string in C++?
http://www.daniweb.com/software-development/cpp/threads/27905
Hope this helps, though I am not proficient C/C++ programmer. For the record it would be nice if you could specify in the tags or in post language you are using.
Tokenizer.h
#ifndef TOKENIZER_H
#define TOKENIZER_H
#include <string>
#include <vector>
#include <sstream>
class Tokenizer
{
public:
Tokenizer();
~Tokenizer();
void Tokenize(std::string& str, std::vector<std::string>& tokens);
};
#endif /* TOKENIZER_H */
Tokenizer.cpp
#include "Tokenizer.h"
using namespace std;
string seps(string& s) {
if (!s.size()) return "";
stringstream ss;
ss << s[0];
for (int i = 1; i < s.size(); i++)
ss << '|' << s[i];
return ss.str();
}
void tok(string& str, vector<string>& tokens, const string& delimiters = ",")
{
seps(str);
string::size_type lastPos = str.find_first_not_of(delimiters, 0);
string::size_type pos = str.find_first_of(delimiters, lastPos);
while (string::npos != pos || string::npos != lastPos)
{
tokens.push_back(str.substr(lastPos, pos - lastPos));
lastPos = str.find_first_not_of(delimiters, pos);
pos = str.find_first_of(delimiters, lastPos);
}
}
Tokenizer::Tokenizer()
{
}
void Tokenizer::Tokenize(string& str, vector<string>& tokens)
{
tok(seps(str), tokens);
}
Tokenizer::~Tokenizer()
{
}
To tokenize a string
#include "Tokenizer.h"
#include <string>
#include <vector>
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{
// Required variables for later below
vector<string> t;
string s = "This is one string,This is another,And this is another one aswell.";
// What you need to include:
Tokenizer tokenizer;
tokenizer.Tokenize(s, t); // s = a string to tokenize, t = vector to store tokens
// Below is just to show the tokens in the vector<string> (c++11+)
for (auto c : t)
cout << c << endl;
system("pause");
return 0;
}