#include <iostream>
#include <cctype>
using namespace std; //I know it's nooby, but i dont care atm.
int main(void)
{
char temp;
int value;
cout << "Write a value: ";
cin >> temp;
while (isdigit(temp) && temp >= 0)
{
value = temp;
cout << "The value is " << value;
cout << "Write a new value: ";
cin >> temp;
}
cout << "Press any key to continue.";
cin.get();
cin.get();
return 0;
}
weird C++ thingy
Author
Ok guys, i need a code that will make the user input something and input it until the user either enters a letter or a negative number. And it must be able to handle values like 100000 and such. so how do i do this?
this is what i have:
edit : oops i forgot to say some things, but the thing is that char can't handle big amounts, i think CHAR_MAX on my comp is 127 or something, and int can't handle letters. So how do i fix this? Should i use some sort of array or something? :s
Look at the gets functions. (gets, fgets, ...)
and use a buffer : char buffer[128] for exemple.
atoi is a function to convert a string to an integer.
hope that helps.
neyna
and use a buffer : char buffer[128] for exemple.
atoi is a function to convert a string to an integer.
hope that helps.
neyna
dont forget : #include
#include
int main() {
char buffer[128];
while( strcmp(gets(buffer),"quit")!=0 ) {
printf("You wrote : %s\n",buffer);
}
return 0;
}
neyna
#include
int main() {
char buffer[128];
while( strcmp(gets(buffer),"quit")!=0 ) {
printf("You wrote : %s\n",buffer);
}
return 0;
}
neyna
off the top of my head, might not be syntaticaly correct but
i hope you get the idea, if not, query me back.
PS. i hope that wasnt a homework assignment, because if it was
your cheating nobody but yourself.
i hope you get the idea, if not, query me back.
#include <cstdio>#include <iostream>using namespace std;bool isNumber(const char *str){ // may need to trim str for leading/trailing whitespace int start = 0; if( str[0] == '-' ) // handle negatives too start++; for(int i=start; i<strlen(str); i++) if( !isdigit(str) ) return false; return true;}int main(){ bool done = false; char temp[40] = {0}; // 40 chars should be enough int ival = 0; while( !done ) { cout << "The value is " << temp; cout << "Write a new value: "; cin >> temp; bool isNum = isNumber(temp); if( isNum ) ival = atoi(temp); if( isNum && ival < 0 || !isNum ) // if its negative OR a string done = true; }}PS. i hope that wasnt a homework assignment, because if it was
your cheating nobody but yourself.
Author
I dont really understand, how would the code be?
edit: i only saw the first post after mine. you guys are fast at typing. thanks all :d
edit: i only saw the first post after mine. you guys are fast at typing. thanks all :d
Quote:Original post by Tobbe
I dont really understand, how would the code be?
#include <stdio.h>int main() { char buffer[128]; int number=0; while( strcmp(gets(buffer),"quit")!=0 ) { printf("You wrote : %s\n",buffer); number=atoi(buffer); // .......... } return 0;}hope that helps.
neyna
Author
ok thank you all. I just thought that it might be an easier or obvious way to do it. But i will try to construct a longer function instead.
And it's not homework because i dont have programming in school :(
Btw, what's the difference between this:
and this:
And it's not homework because i dont have programming in school :(
Btw, what's the difference between this:
char blabla = 5;int blablabla = atoi(blabla);and this:
char blabla = 5;int blablabla = (int) blabla;
quick explination of my code example
while done is false get user input test if it is numberic if( numeric ) convert to integer value if( numeric and less than zero OR is not numeric ) set done = trueloop
atoi takes a const char* argument, and does a char by char
conversion (so its guaranteed to be numeric)
casting from a char to an int works but only if the char
is a digit (between '0' and '9') this is because ASCII digits
map directly to their values BUT letters etc. do not.
eg. try this
conversion (so its guaranteed to be numeric)
casting from a char to an int works but only if the char
is a digit (between '0' and '9') this is because ASCII digits
map directly to their values BUT letters etc. do not.
eg. try this
char a = '3';int val = (int) a;cout << val << endl;------------------------------char a = 'z';int val = (int) a;cout << val << endl;This topic is closed to new replies.
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