The task of this function is to check, whether it contains any symbols but digits, spaces, or minuses.
bool MainWindow::inputExcp()
{
QString inputStr = ui->input->toPlainText();;
QByteArray ba = inputStr.toLocal8Bit();
char *myString = ba.data();
QString warn;
char space = ' ';
size_t size = sizeof(myString);
try{
for(unsigned long long i = 0; i < size; i++)
{
if (isdigit(*(myString+i)))
continue;
else if (*(myString+i) == space)
continue;
else if(*(myString+i) == '-')
continue;
else
throw *(myString+i);
}
}
catch (char x)
{
warn += ("Enter digits, spaces or minuses");
QMessageBox::warning(this, "Uncorrect input",warn);
return false;
}
return true;
}
I can't understand why this function returns true only for arrays that contain 8 and more elements. What is the solution to this problem?
Because the sizeof() function doesnt return the number of elements of a list, it returns the the size of the memory allocated for it.
Related
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 asked a question here and now the code below makes the work that I expected (the work that I mentioned previously). Now I have another issue: if I write tmp[20] and if the size of the input is 20 chars, the code works. However the size of the input is not known. Therefore, there can be a maxsize, but the actual size depends on the input. How can I make this code work with every length? (yes, the code works when I write 200 inside of tmp but the size of 'message' depends on the whole array. It should be 3 chars before end and 6 chars after start).Therefore when I write 200 inside of tmp[] and the input is shorter than 200 chars, the message returns incorrectly. I think I should use dynamic memory allocation but I could not implement it to my code.
Here is my complete code:
char tmp[20] = { 0 };
int len = sizeof(tmp) / sizeof(tmp[0]);
String pack;
String command;
String Size;
String messum;
String message;
String checksum;
int Index = 0;
bool Seen = false;
void setup() {
Serial.begin(9600);
}
void loop() {
while (Serial.available() > 0) {
char received = Serial.read();
if (received == '!') {
Seen = true;
} else
if (received == '#') {
return strdup(tmp);
} else
if (Seen == true) {
if (Index < 2) {
//Serial.print("P");
pack = tmp[Index++] = received;
Serial.print(pack);
} else
if (Index < 4) {
//Serial.print("C");
command = tmp[Index++] = received;
Serial.print(command);
} else
if (Index < 6) {
//Serial.print("S");
Size = tmp[Index++] = received;
Serial.print(Size);
} else
if (Index < (len - 3)) {
//Serial.print("M");
message = tmp[Index++] = received;
Serial.print(message);
} else
if (Index < len) {
//Serial.print("C");
checksum = tmp[Index++] = received;
Serial.print(checksum);
}
}
}
return NULL;
//input: asdeyh134!123456789abcdefghtry#8647dfn
}
Anywhere you are adding characters to your array like this:
if (Seen == true) {
if (Index < 2) {
//Serial.print("P");
pack = tmp[Index++] = received;
Serial.print(pack);
You should also null terminate your string like so:
if (Seen == true) {
if (Index < 2) {
//Serial.print("P");
pack = tmp[Index++] = received;
tmp[Index] = 0;
Serial.print(pack);
That way you can use strlen to get the length of the string in the array. It will count the number of characters up to that null character.
int length = strlen(tmp);
On the next pass of the loop when you write in another character you will write it over that null and then write a new null right after that new character.
I am programming my custom string class with multiple methods. The issue is that the comparison method does not work as I intend. Instead of doing nothing when the two char arrays differ, an if conditional still proceeds in my main function.
There are no errors given when I compile with g++. The code is syntactically correct, however logically faulty. I know this because I can give the compare method two char arrays which differ in content, and it will not matter whether they differ this way, as the main function will run the if conditional for "s8.compare(s7) == 1" regardless if the result in the compare method is not true.
I will post the entire code below. Any help is greatly appreciated.
string.h
class Str {
private:
char *value;
int length;
int capacity;
//Doubles the size of the string when called.
void growArray();
//If the two strings are uneven, get absolute value of difference in length.
int difference(int a, int b);
//Calculates the size of a character array, passed in as an argument
int getCharArrSize(const char *v);
public:
Str();
explicit Str(const char *STR);
void copy(Str s);
void concatenate(Str s);
bool compare(Str s);
void print();
};
//Str constructor
Str::Str() {
//Assign value, capacity, and length to any new Str object
value = new char[100];
capacity = 100;
length = 0;
}
//Pass STR object as a pointer to string object constructor
Str::Str(const char *STR) {
length = getCharArrSize(STR);
capacity = 100;
value = new char[capacity];
//Copy contents from STR to string object
for (int i = 0; i < length; i++)
value[i] = STR[i];
}
//Doubles the size of the string when called.
void Str::growArray() {
const char *tmp = value;
capacity *= 2;
value = new char[capacity];
for (int i = 0; i < length; i++)
value[i] = tmp[i];
}
//If the two strings are uneven, get absolute value of difference in length.
int Str::difference(int a, int b) {
int d = 0;
if (a > b) d = a - b;
else if (b > a) d = b - a;
return d;
}
//Calculates the size of a character array, passed in as an argument
int Str::getCharArrSize(const char *v) {
int c = 0;
while (v[c] != '\0') {
c++;
}
return c;
}
//Overwrites the data of the string array with the data contained in s
void Str::copy(Str s) {
//Check ability for empty string object to hold Str s contents
if (capacity > s.length) {
//Copy over each element until s length is reached
for (int i = 0; i < s.length ; i++)
value[i] = s.value[i];
//Set string object length to copy's size
length = getCharArrSize(value);
} else { growArray(); }
}
//Concatenate Str s onto string object
void Str::concatenate(Str s) {
//Check ability for string object to hold itself and concatenated chars
if (capacity > length + s.length) {
//Fill string object with s object until end of combined lengths if necessary
for (int i = 0; i < length + s.length; i++)
value[length + i] = s.value[i];
//Set length based on chars in concatenated string object
length = getCharArrSize(value);
} else { growArray(); }
}
//Compare each element in Str s against string for similarities
bool Str::compare(Str s) {
if (length == s.length) {
if (*value == *s.value) {
while ((*value != value[length]) && (*s.value != s.value[s.length])) {
value++;
s.value++;
}
return true;
} else return false;
} else {
difference(length, s.length);
}
}
//Print function
void Str::print() {
std::cout << value << std::endl;
}
main.cpp
#include"string.h"
int main() {
Str s1("Hello ");
Str s2("World");
Str s3(", my ");
Str s4("Name ");
Str s5("is ");
Str s6("Chad!");
Str s7;
s7.copy(s1);
s7.concatenate(s2);
s7.concatenate(s3);
s7.concatenate(s4);
s7.concatenate(s5);
s7.concatenate(s6);
s7.print();
std::cout << "\n\n";
Str s8("Hello World, My Name is Chad!");
if (s8.compare(s7) == 1) {
std::cout << "They Match!" << std::endl;
}
Str s9("I dont match....");
if (s9.compare(s8) == 0) {
std::cout << "I differ by " << s8.compare(s6) << " characters" << std::endl;
}
}
The above code returns a result that appears correct, however changing (s8.compare(s7) == 1) to something like (s8.compare(s5) == 1) returns 'They match!' when I am trying to check each individual element in the char arrays against one another, and only return true if they are the same length and each character matches in the arrays.
Your program has undefined behavior since Str::compare does not have a return statement in one of the branches.
bool Str::compare(Str s) {
if (length == s.length) {
...
} else {
// Missing return statement.
difference(length, s.length);
}
}
Perhaps you want to change that line to:
return (difference(length, s.length) == 0);
Your loop is running without a comparison. You compare the initial values in the char array and then loop through the rest without comparison. So you will return true every time the initial values are equal.
Below the loop runs after the same length is determined then every char is compared. If they are not equal then the function will return false. Otherwise the function will return true.
bool Str::compare(Str s) {
if (length == s.length) {
while ((*value != value[length]) && (*s.value != s.value[s.length])) {
if (*value == *s.value) {
value++;
s.value++;
} else {
return false;//will return false as soon as a comparison is false
}
}
return true;
} else {
difference(length, s.length);
}
}
You also need to return a boolean from the difference function. If you want to return ints from that function switch to a int return on the compare function and use 0 and 1s as their boolean counterparts.
I am having the following problem with my code, though it compiles correctly:
value type const char cannot be used to initialize an entity of type char*
Can someone help me? I can run the code which is weird but I can't create a makefile using this. It's very weird to me.
int SpliString(struct dict_word *entry, const char *str)
{
long word_length,j,k;
int yearIndex;
char *buffer;
char *endOfYears;
char *endOfYear;
char *endOfDefinition;
char *endOfWord = strstr(str, "_#_");
//Sets the first num bytes of the block of memory pointed by ptr
//to the specified value (related as an unsigned char)
memset(entry, 0, sizeof(struct dict_word));
// If '_#_' is not found, it's NULL
if (endOfWord)
{
// Calculating word legth; 'str' points to start of word, 'endofWord' points to '_#_' that is just after word
word_length = endOfWord - str;
// Copying data into the word
strncpy(entry->words, str, word_length);
// 'endOfYears' points to '_#_,' but wee need to find follow '_#_'
// therefore there is added 3 in order to skip curremnt '_#_
endOfYears = strstr(endOfWord+3, "_#_");
if (endOfYears)
{
word_length = endOfYears - (endOfWord+3);
// Skips _#_
buffer = endOfWord+3;
yearIndex = 0;
j = 0;
// Finds next year in the line, it stops if all 10 years is filled
// or end of years string is reached
while(yearIndex<10 && buffer+j<endOfYears)
{
// Stores year in the buffer, with converting 'stirng' to 'int'
entry->year[yearIndex] = atoi(buffer+j);
// check year for negative...
if (entry->year[yearIndex]<=0)
return 0;
// Locating substring; 'j' is current offset from beginning of buffer
endOfYear = strchr(buffer+j, '_');
if (endOfYear)
{
j = endOfYear - buffer;
j++;
yearIndex++;
}
else
{
break;
}
}
//endOfYears points to '_#_' that separatates 'years' and 'definition'
//and there is needed to find '_#_' between 'definition' and 'synonyms'
//therefore it skips '_#_' that separatates 'years' and 'definition',
//+3, because '_#_' has length = 3
endOfDefinition = strstr(endOfYears+3, "_#_");
if (endOfDefinition)
{
word_length = endOfDefinition - (endOfYears+3);
k = 0;
for(j=0; j<word_length; j++)
{
// Skips '_#_'
if (endOfYears[j+3]==',')
{
entry->eng_synonyms[k] = ' ';
k++;
}
else if (endOfYears[j+3]>='a' && endOfYears[j+3]<='z')
{
entry->eng_synonyms[k] = endOfYears[j+3];
k++;
}
else if (endOfYears[j+3]!='_')
{
return 0;
}
}
k = 0;
word_length = (str+strlen(str)) - (endOfDefinition+3);
for(j=0; j<word_length; j++)
{
if (endOfDefinition[j+3]==',')
{
entry->heb_synonyms[k] = ' ';
k++;
}
else if (endOfDefinition[j+3]>='A' && endOfDefinition[j+3]<='Z')
{
entry->heb_synonyms[k] = endOfDefinition[j+3];
k++;
}
else if (endOfDefinition[j+3]!='_')
{
return 0;
}
}
}
// Check for legality
// Check all symbols of 'entry->words'
// calculate length and supress warning
for(j=0;j<(int)strlen(entry->words);j++)
{
if (entry->words[j]<'a' || entry->words[j]>'z')
return 0;
}
return 1;
}
}
return 0;
}
Use
const char *buffer;
const char *endOfWord = strstr(str, "_#_");
Confident OP is compiling in C++.
// C
char *strstr(const char *s1, const char *s2);
// C++
const char* strstr(const char* s1, const char* s2);
char* strstr( char* s1, const char* s2);
See
Compile C app with Visual Studio 2012
How to compile and execute C program on Visual Studio 2012 for Windows 8?
I have one array of WCHAR is like this
WCHAR Path[256];
So I'm passing this array in my function getpath(Path) and It's filling the value in path like this:
//device/systemName/
So I want to get only device from above string.
My code is here:
WCHAR *pDevName;
int i = 0;
int j = 0;
while(Path[i] != NULL){
if(0 ==(wcscmp(Path, L"/")))
{
//i = i + 2;
++i;
continue;
}
else
{
pDevName[j] = Path[i];
++i;
++j;
if (0 == wcscmp(Path, L"/")){
break;
}
}
My code is getting compiled but it's not returning for me device from WCHAR array. It's returning //devicename/systemName/, which is coming from pDevName.
I have doubt over my comparison on wcscmp(). So my question is how to compare / with remaining wchar array value.
wcscmp compares a string, not a character. You're also passing the same address to wcscmp every time - Path, which means all you're doing is comparing the whole string against "/", which will always fail.
If you want to test a single character you can simply compare its value directly, for example:
WCHAR *pDevName;
// NB: I assume you are allocating pDevName and just left that out of the code
// for brevity.
int i = 0;
int j = 0;
while(Path[i] != L'\0'){
if(Path[i] == L'/')
{
++i;
continue;
}
else
{
// NB: you should check for overflow of pDevName here
pDevName[j++] = Path[i++];
if (Path[i] == L'/')
break;
}
}
Since you specified c++, it would be easier to do something like this:
#include <string>
using namespace std;
wstring get_device_name(const wchar_t* path)
{
wstring source(path);
wstring device_name;
if (source.substr(0, 2)==L"//")
{
size_t position= source.find(L'/', 2);
if (position==wstring::npos)
device_name= source.substr(2);
else
device_name= source.substr(2, position-2);
}
return device_name;
}