im creating a hangman game that has to use CHAR and not strings. I was wondering how i would choose a single random word form a Char array and display it to the console as a symbol e.g. ****** instead of the word. My current array; Thank you.
char words [6][10] =
{
"Pistachio",
"Avocado",
"Salami",
"Bologna",
"Christmas",
"Giraffes",
};
This is what i have so far (i know it not much im a bit confused)
cout <<"Test " <<words <<endl;
and that just out put a random number ??
To output a cstring from an array of cstrings you need to provide the index of that string.
cout <<"Test " <<words <<endl;
Will just print the address of the first element of the array since that is what an array name is reduced to. So the correct way to display from the array is:
cout <<"Test " <<words[indexOfTheStringYouWant] <<endl;
words is a char** an array of char[10]. The << operator knows how to print simple types (int, float), std::string and char *, but not char ** arrays nor pointers to C strings (char arrays). So it only print the address of the array of char *. char[10]
I think that what you want is :
for (int i=0; i< sizeof(words)/sizeof(char *); i++) cout << words[i] << " ";
cout << endl;
If I have understood correctly what you need is the following
#include <iostream>
#include <algorithm>
#include <numeric>
#include <cstdlib>
#include <ctime>
int main()
{
const size_t N = 6;
const size_t M = 10;
char words[N][M] =
{
"Pistachio",
"Avocado",
"Salami",
"Bologna",
"Christmas",
"Giraffes",
};
size_t index[N];
std::iota( index, index + N, 0 );
std::srand( ( unsigned int )std::time( nullptr ) );
std::random_shuffle( index, index + N );
for ( size_t i = 0; i < N; i++ ) std::cout << words[index[i]] << std::endl;
return 0;
}
The program output might look like
Giraffes
Bologna
Pistachio
Avocado
Salami
Christmas
I think you are looking for this:
#include<cstdlib>
int v;
for(int i=0; i<10; i++)
{
v = rand() %6;
printf("%s\n", words[v]);
}
Related
I'm a new Computer Science student, and I have a homework question that is as follows:
Write a Function that passes in a C-String and using a pointer determine the number of chars in the string.
Here is my code:
#include <iostream>
#include <string.h>
using namespace std;
const int SIZE = 40;
int function(const char* , int, int);
int main()
{
char thing[SIZE];
int chars = 0;
cout << "enter string. max " << SIZE - 1 << " characters" << endl;
cin.getline(thing, SIZE);
int y = function(thing, chars, SIZE);
cout << y;
}
int function(const char *ptr, int a, int b){
a = 0;
for (int i = 0; i < b; i++){
while (*ptr != '\0'){
a++;
}
}
return a;
}
First of all welcome to stackoverflow ye0123! I think you are trying to rewrite the strlen() function here. Try giving the following link a look Find the size of a string pointed by a pointer.
The short answer is that you can use the strlen() function to find the length of your string. The code for your function will look something like this:
int function(const char *ptr)
{
size_t length = strlen(ptr);
return length;
}
You should also only need this function and main.
Edit: Maybe I misunderstood your question and you are supposed to reinvent strlen() after all. In that case, you can do it like so:
unsigned int my_strlen(const char *p)
{
unsigned int count = 0;
while(*p != '\0')
{
count++;
p++;
}
return count;
}
Here I am comparing *p from '\0' as '\0' is the null termination character.
This was taken from https://overiq.com/c-programming-101/the-strlen-function-in-c/
I cannot use any c functions except strlen(), and I also cannot use strings. I have been at this for an unfortunate amount of time. I keep getting weird characters as part of the output. i.e question marks and essentially weird alt codes is what it looks like.
#include <iostream>
#include <cstring>
using namespace std;
int lastIndexOf(const char*, char[]);
void reverse(char*);
int replace(char*, char, char);
int main() {
int i = 0, count = 0, counter = 0, SIZE = 100;
char charArray[SIZE];
cout << "Enter a string of no more than 50 characters: ";
cin.getline(charArray, SIZE);
reverse(charArray);
}
void reverse(char s[])
{
int n = 100;
for (int i = 0; i < n / 2; i++) {
swap(s[i], s[n - i - 1]);
cout << (s[i]);
}
}
I have tried several different things, swap function, using pointers to manually swap them with a temp variable. So I went to the internet to see what other people did, but to no avail. I am convinced there is a simple solution.
The function uses a magic number 100
int n = 100;
though in main there is a prompt to enter no more than 50 characters.
cout << "Enter a string of no more than 50 characters: ";
You need to calculate the length of the passed string by using the standard C function strlen.
The function can look the following way
char * reverse( char s[] )
{
for ( size_t i = 0, n = std::strlen( s ); i < n / 2; i++ )
{
std::swap( s[i], s[n-i-1] );
}
return s;
}
Pay attention to that variable length arrays is not a standard C++ feature.
You should write
const size_t SIZE = 100;
char charArray[SIZE];
As part of my homework assignment, I have to split a char[] by its indices. So for example, the main function looks like:
int main()
{
char str[] = "A string to be split into given number of parts";
int split_size;
cout << "Enter the size of the part: ";
cin >> split_size;
int size = sizeof(str) / sizeof(str[0]);
SplitString(str, split_size, size);
int wait;
cin >> wait;
return 0;
}
Then using the function SplitString, the first x elements are printed, new line, then the next.
My first idea, was to use two for loops. One loops through the splits (i.e. if there are 4 splits, the range on this loop is 0 to 3), then the second loops through the split itself, iterating over the array elements.
My SplitString() function looks like this:
void SplitString(char str[], int split_size, int size) {
int parts = size / split_size;
for (int i = 0; i < parts; i++) {
for (int j = 0; j < split_size; j++) {
j = split_size * i;
cout << str[j];
}
cout << endl;
}
}
Is there an easier way to do this? I know in Python, you can use the arr[1:] to grab a range of elements from the array. Is there anything similar in C++? Is there some flaw in my logic? Is there something wrong with my code?
cout comes with a write function that takes a pointer and a size argument.
for (int i = 0; i < parts; i++) {
cout.write (str+i*split_size, split_size)
cout << endl;
}
Note that the code above does not check if the string is actually long enough. If the total size is not equal the split_size times a whole number, you will have to add an additional check.
Also, note that this:
int size = sizeof(str) / sizeof(str[0]);
can be written as:
int size = sizeof(str);
instead because the size of a char is always 1.
You can use std::string for this. Alternatively, if your compiler supports C++17, you can use std::string_view as the first argument of SplitString to avoid unnecessary copying.
#include <algorithm>
#include <iostream>
#include <string>
void SplitString(std::string s, std::size_t split_size)
{
while(!s.empty())
{
auto size = std::min(split_size, s.size());
std::cout << s.substr(0, size) << '\n';
s = s.substr(size, std::string::npos);
}
}
int main()
{
char str[] = "A string to be split into given number of parts";
int split_size = 5;
SplitString(str, split_size);
return 0;
}
Live example.
I wrote the following to try to use the qsort() function. My goal is to input several lines of text and print an alphabetical listing of each word. This code crashes every time I run it and i am not sure as to why or how to fix it. I also need to add something to count the number of times a word occurs and print that as well but I an mot too sure how to do that. Any advice would be very helpful. Thanks!
#include <algorithm>
#include <iostream>
#include <string>
using namespace std;
struct to_lower
{
int operator() ( int ch )
{
return tolower ( ch );
}
};
int compare (const void * a, const void * b)
{
//return ( *(int*)a - *(int*)b );
return (strcmp(*(const char **)a, *(const char **)b));
}
int main()
{
string list[900];
int nLength;
int i=0, q=0;
string nTemp;
int word[900];
cout
<< "Enter some lines of text "
<< "(Enter Ctrl-Z on a line by itself to exit)\n"
<< endl;
while ( !cin.eof() )
{
cin >> list[i];
transform(list[i].begin(), list[i].end(), list[i].begin(), to_lower());
word[q]=1;
if (list[i]==list[i-1])
{
word[q]=+1;
}
i++;
}
nLength = i;
cout << "The sorted words would be:\n";
qsort(list, nLength, sizeof list[0],&compare);
int n;
for (n = 0; n < nLength; n++)
{
cout <<" \n"<< n << list[n]<< word[n];
}
return 0;
}
std::string is not a char* as your qsort compare function pretends. Also, you should never use qsort with C++ objects. qsort does not know about objects and won't call copy constructors and may damage the internal structure.
When i=0, using list[i-1] is a bug.
You need to count your duplicate words after sorting or you have no guarantee that duplicates are next to each other.
#include <iostream>
using namespace std;
int main(){
int findMax(int *);
const int MAX = 100;
int values[MAX];
char ivals[256];
// Get the space-separated values from user input.
cin.getline(ivals, 256, '0');
char *helper;
// Clean input array and transfer it to values.
for(int i = 0; i < (MAX) && ivals[i] != 0; i++){
helper = ivals[i * 2];
values[i] = atoi(helper);
}
int mval = findMax(values);
cout << values << endl << mval;
return 0;
}
//Function to find the maximum value in the array
int findMax(int arr[]){
int localmax = 0;
for(int i = 0; i < (sizeof(arr)/sizeof(int)); i++){
if(arr[i] > localmax){
localmax = arr[i];
}
}
return localmax;
}
The purpose of this program is for the user to input a space-separated series of values ended by a 0. That array is then to be analyzed to find the max. I figured out how to convert what is originally a char[] into an int[] so that I can use the findMax() function on it without error but the sorting loop seems to have a problem of its own and when "cout << values << endl << mval;" is called, it returns only a memory address instead of what should be a non-spaced sequence of ints. Can anybody explain what I am doing wrong? It seems that I may have made some mistake using the pointers but I cannot figure out what.
Printing values won't print the contents of the array as you expect, it will print the memory location of the first element of the array.
Try something like this instead:
#include <iterator>
#include <algorithm>
// ...
copy(&values[0], &values[MAX], ostream_iterator(cout, " "));
Sorry I can't post actual working code, but your original post is a mess with many syntax and syntactic errors.
EDIT: In the interest of being more complete and more approachable & understandable to beginners, I've written a small program that illustrates 4 ways to accomplish this.
Method 1 uses copy with an ostream_iterator as I've done above.
Method 2 below is probably the most basic & easiest to understand.
Method 3 is a C++0x method. I know the question is tagged C++, but I thought it might be educational to add this.
Method 4 is a C++ approach using a vector and for_each. I've implemented a functor that does the dumping.
Share & Enjoy
#include <iostream>
#include <iterator>
#include <algorithm>
#include <functional>
#include <vector>
using namespace std;
struct dump_val : public unary_function<int,void>
{
void operator()(int val)
{
cout << val << " ";
}
};
int main(){
int vals[5] = {1,2,3,4,5};
// version 1, using std::copy and ostream_iterator
copy(&vals[0], &vals[5], ostream_iterator<int>(cout, " "));
cout << endl;
// version 2, using a simple hand-written loop
for( size_t i = 0; i < 5; ++i )
cout << vals[i] << " ";
cout << endl;
// version 3, using C++0x lambdas
for_each(&vals[0], &vals[5], [](int val)
{
cout << val << " ";
}
);
cout << endl;
// version 4, with elements in a vector and calling a functor from for_each
vector<int> vals_vec;
vals_vec.push_back(1);
vals_vec.push_back(2);
vals_vec.push_back(3);
vals_vec.push_back(4);
vals_vec.push_back(5);
for_each( vals_vec.begin(), vals_vec.end(), dump_val() );
cout << endl;
}
When you pass around an array of X it's really a pointer to an array of X that you're passing around. So when you pass values to cout it only has the pointer to print out.
You really should look into using some of the standard algorithms to make your life simpler.
For example to print all the elements in an array you can just write
std::copy(values, values+MAX, std::ostream_iterator<int>(std::cout, "\n"));
To find the max element you could just write
int mval = *std::max_element(values, values+MAX);
So your code becomes
#include <iostream>
using namespace std;
int main(){
const int MAX = 100;
int values[MAX];
char ivals[256];
// Get the space-separated values from user input.
cin.getline(ivals, 256, '0');
char *helper;
// Clean input array and transfer it to values.
for(int i = 0; i < (MAX) && ivals[i] != 0; i++){
helper = ivals[i * 2];
values[i] = atoi(helper);
}
copy(values, values+MAX, ostream_iterator<int>(cout, "\n"));
cout << *std::max_element(values, values+MAX);
return 0;
}
Doing this removes the need for your findMax method altogether.
I'd also re-write your code so that you use a vector instead of an array. This makes your code even shorter. And you can use stringstream to convert strings to numbers.
Something like this should work and is a lot less code than the original.
int main(){
vector<int> values;
char ivals[256];
// Get the space-separated values from user input.
cin.getline(ivals, 256, '0');
int temp = 0;
stringstream ss(ivals);
//read the next int out of the stream and put it in temp
while(ss >> temp) {
//add temp to the vector of ints
values.push_back(temp);
}
copy(values.begin(), values.end(), ostream_iterator<int>(cout, "\n"));
cout << *std::max_element(values.begin(), values.end());
return 0;
}
Array of int is promoted to a pointer to int when passed to a function. There is no operator << taking ordinary array. If you want to use operator << this way, you need to use std::vector instead.
Note: it is possible technically to distinguish array when passed to a function using template, but this is not implemented for standard operator <<.
for(int i = 0; i < (sizeof(arr)/sizeof(int)); i++){
sizeof(arr) here is the size of the pointer to the array. C++ will not pass the actual array, that would be grossly inefficient. You'd typically only get one pass through the loop. Declare your function like this:
int findMax(int* arr, size_t elements) {
//...
}
But, really, use a vector.
Oh, hang on, the question. Loop through the array and print each individual element.