Make Me A Better Programmer - From Step 1 - Topic

AbDuCt

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#121

Sep 16 2012 10:55pm

i always thought the .length() method returned integers anyways. that would be a useless cast if i was correct.

Eep

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#122

Sep 17 2012 12:40am

Quote (AbDuCt @ Sep 16 2012 11:55pm)

i always thought the .length() method returned integers anyways. that would be a useless cast if i was correct.

it returns size_t

AbDuCt

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#123

Sep 17 2012 07:11am

Quote (Eep @ Sep 17 2012 02:40am)

it returns size_t

size_t is just an unsigned integer and when you cast it to int() you are just casting it to a signed integer. no difference really unless you specifically need one of the other.

Eep

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#124

Sep 17 2012 09:35am

I didn't know what size t was so I casted them

Eep

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#125

Oct 3 2012 01:25am

2nd project complete (reverse polish calculator)

Code

#include <iostream>
#include <string>
#include <stdlib.h>
using namespace std;

struct stack
{
int value;
stack *next;
};

stack *calcStack = NULL;

void push(int num);
int pop();
void operation(char op);
void operation2(char op);
bool opCheck(char op);
int main()
{
char temp[20];
while(cin >> temp)
{
if (isdigit(temp[0]))
{
push(atoi(temp));
}
else if (opCheck(temp[0]))
{
operation(temp[0]);
}
else
{
operation2(temp[0]);
}
}
return 0;
}

void push(int num)
{
stack *newItem = new(stack);
newItem->value = num;
newItem->next = calcStack;
calcStack = newItem;
}

int pop()
{
int item = calcStack->value;
stack *tempPtr = calcStack;
calcStack = calcStack->next;
delete tempPtr;
return item;
}

void operation(char op)
{
int num1, num2;
num1 = pop();
num2 = pop();

switch(op)
{
case '+':
push(num2+num1);
break;
case '-':
push(num2-num1);
break;
case '*':
push(num2*num1);
break;
case '/':
push(num2/num1);
break;
default:
break;
}
}

void operation2(char op)
{
int num;
switch(op)
{
case 'u':
num = pop();
push(-num);
break;
case 'p':
num = pop();
cout << num << endl;
break;
case 'e':
cout << "Thanks for using the reverse polish calculator." << endl;
exit(0);
default:
break;
}
}

bool opCheck(char op)
{
if (op == '+' || op == '-' || op == '*' || op == '/')
{
return true;
}
return false;
}

Eep

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#126

Oct 25 2012 06:24pm

My 3rd project worked the first time!! Made a few simple mistakes (missing a semicolon here and there) and had some issues with pointers which I will discuss in a sec

project requirements:

Quote

For your third project, you are to write a program to create a frequency list
of words in a passage.

A frequency list is a list of the distinct words in the
passage together with a cout of the number of times that word occurs.

The input will be read from stdin [i.e., cin]. The output is to be sent to
stdout [i.e., cout], sorted alphabetically on the words.

I want you, for each word that is read, to convert all the characters to lower
case [so that The and the are counted together] and if the word ends in a
punctuation symbol, to remove it [you may assume that there is at most one
punctuation mark].

You can use a binary tree, sorted on the words, to hold the words and their
counts. If a word is seen again, increment the count.

here is the code:

MAIN:

Code

#include <iostream>
#include "tree.h"
#include <string>
#include <ctype.h>

using namespace std;

int main()
{
string word;
string::iterator it;
int strlen;
tNode *root = NULL;

while (cin >> word)
{
it = word.end()-1;
strlen = word.length();
if (ispunct(word[strlen-1]))
{
word.erase(it);
}
for (int i = 0; i < strlen; i++)
{
word[i] = tolower(word[i]);
}
tAdd(word, root);
}
inOrder(root);

return 0;
}

TREE.CPP

Code

#include "tree.h"
#include <string>
#include <iostream>

using namespace std;

void tAdd(string input, tree & root)
{
if (root == NULL)
{
tNode *node = new(tNode);
node->word = input;
node->counter = 1;
node->left = node->right = NULL;
root = node;
return;
}
if (input == root->word)
{
root->counter++;
return;
}
else if (input < root->word)
{
tAdd(input, root->left);
}
else tAdd(input, root->right);
}

void inOrder(tree root)
{
if (root == NULL)
{
return;
}
inOrder(root->left);
cout << root->word << " has occurred " << root->counter << " time(s)." << endl;
inOrder(root->right);
}

TREE.H

Code

#include <iostream>
#include <string>
using namespace std;

struct tNode
{
string word;
int counter;
tNode *left, *right;
};

typedef tNode *tree;

void tAdd(string word, tree & root);
void inOrder(tree root);

proj. said his main was like 67 lines. I wonder why his was so much longer.

Anyways, a funky issue I was having:

for some reason, if I didn't typedef tNode as *tree, and just passed functions something like

Code

void tAdd(string word, tNode *& root);

it was giving me grief. I saw in the professors examples he did the typedef, and it worked again for some reason. What was I doing wrong exactly? The error I was getting was something along the lines of root not being a member class of tNode*& or something.

This post was edited by Eep on Oct 25 2012 06:30pm

rockonkenshin

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#127

Oct 26 2012 06:51am

This makes me want to pick up C++ again. It's been a really long time since I've written anything meaningful in it and I'm starting to forget everything about it.

Eep

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#128

Oct 26 2012 02:06pm

I am happy that I got my code to be so small this time around. I probably could have gotten it a bit smaller if I knew a bit more

Eep

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#129

Nov 15 2012 11:49am

Soooo I got a new project and I could use some ideas. I posted in the C/C++ forum but I think even general advice could help

here is the thread:

http://forums.d2jsp.org/topic.php?t=65257988&f=122

if anyone could offer some suggestions let me know.

Eep

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Gold: 20.00

#130

Nov 18 2012 04:48am

I am rather confuzzled still. Could someone (proficient in c++) at least tell me if I am even getting WARMER? Here is my latest pseudo-but-not code:

IDEA: I want a function to parse lines of input. The inputs are coming from a file which is being sent to the program right after compiling eg:

Code

g++ proj4.cpp < some_input_file

I need the function to sort thru lines of inputs like:

Code

Steve1 12Nov1931 M Mary1 17Dec1833 Steve2 Harry1 Sue1 3Jan1959 X
Steve2 31Dec1957 S Xavier1 X

(THESE ARE 2 POSSIBLE LINES OF INPUT I SHOULD EXPECT IN MY PROGRAM)

I need to fill the class's data fields. More explanation is done in that thread I posted above!!

anyway, here is 30 mins worth of me thrusting my head against the keyboard has produced:

Code

void someFunction (string temp, Person & head)
{

int delim;
string data;
head = new(Person);

while (!temp.empty())
{

delim = temp.find_first_of(" ");

data = temp.substr(0,delim-1);

temp.erase(0,delim-1);

if (head.name.empty())
head.name = data;
else if (head.dob.empty())
head.dob = data;
else if (head.marital.empty())
{
head.marital = data;
if (head.marital == S)
continue;
else
{
head->spouse = new(Person);
head->children = new(kids);
continue;
}
}
else if (head->spouse.name.empty())
head->spouse.name = data;

This post was edited by Eep on Nov 18 2012 04:48am

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