I would just like to know what does
while( (c =getchar())!='
' && c !=EOF );
do ? and how it do it?
I have see it in a example to clear the input buffer for next input through scanf but does not know its working clearly.
it is used in this example :
Code:
#include<stdio.h>
struct linklist {
char value[20];
struct linklist *next;
};
struct linklist *head,*curr;
[Code] .....
I want the user to be able to enter a command then a character, like for example: push r....I want the command to be stored in the array command, and the character to be stored in the variable c.
Now I wonder what the best way to get rid of the space is, using scanf or getchar (see below for code, only thing that I changed between the 2 versions is the statement before the comment "get rid of space")? Or maybe it doesnt matter?
Code:
include <stdio.h>
#define MAX 200
void push(char c); // Puts a new element last in queue
char pop(void); // Gets the first element in queue
static char s[MAX];
}
[code]....
I am working on a simple calculator in C++ .... All works fine with the calculator up until the requirement for the user to input "do you want to go again y/n" .... What i want to happen is the screen to clear down and reloop to the enter name part....but i can't get it to do that
Program Description: To write and develop a programme where a user can input a cost or price of something before VAT our program must then process the input number and must output the price with the original value plus VAT
#include <iostream>// I must use this to start my programming
#include <string> // I have added this for the extension task so the user has to input their name
#include <iomanip> // this is to manipulate the text
#include <stdlib.h>
using namespace std; // using the "using namespace std" shows that i will be using standard text throughout this programme
[Code] .....
In GCC v4.6, I am encountering a strange problem. If I try to get a character input and a int input like this:
Code:
int main()
{
int a;
char b;
scanf("%d",&a);
scanf("%c",&b);
}
the compiled program asks for input only one time. On the other hand, if I do the char scanf earlier like this:
Code:
int main()
{
int a;
char b;
scanf("%c",&b);
scanf("%d",&a);
}
it asks for input twice.
How to store the value in this case.. The topic is called "limited summation".. The following is the guideline for this problem:
Write a program in a folder called "sum" with a source file of main.cpp that does the following:
•prompt a user to enter a maximum number of entries, make the prompt "max # entries"
•prompt a user to enter a threshold sum, make the prompt "threshold"
•using error checking logic, let a user enter base-10 signed numbers until at least one of the following conditions is true:
or the maximum number of entries is reached
or the sum of entered numbers has reached (>=) the threshold
•print the sum of all the entries, just the number and a linefeed at the end of the line
Error checking means entries that are not numbers are detected and ignored. You are to use printf and scanf in this assignment (no cin or cout).
I tried to scanf the input by the user into the function but it does not read my input. Read on one of the thread, it said that to scanf a input into a double, need to use %1f instead to %d (which normally used. I tried changing it to %1f and it still did not work.
Code:
#include <stdio.h>
#include <math.h>
/* function main begins program execution */
int main( void )
{
double amount; /* amount on deposit */
[Code] ....
so i'm using scanf() this way
Code:
int i;
while (scanf("%i", &i))
printf("%i ", i);
printf("
done
");
i tried several combination of Ctrl+D and "Enter", it's not terminating, Ctrl+C just "cancels" the whole thing without printing "done", i'm running this on linux installed on a PC
So running the following code
Code:
#include <stdio.h>
int main(void) {
char c;
int i=1;
while (scanf("%c", &c)==1)
printf("loop sequence %i: %c(%i)
[Code] ......
Done it seems a "carriage return" serves two purposes here, one is to signal the program to read in the character typed in before the "carriage return", another serves as a second character typed, how can i do this cleanly, that is without having to use a "carriage return" as the second character to signal "I've typed in the first character already".
The issue that I'm having is that when I run this part of the code it seems to enter the if statement and set it to 0 when comparing the array to the input.
What I want it to do is to search the array for the grade, set it to zero, and then exit the loop in case there are any repeat grades. It always sets the first number to 0 and then exits.
//Below is the prototyping for the array
int grades[14] = {60,50,50,20,75,90,0,0,0,0,0,0,0,0};
//There is some code between here, but it is probably not relevant so I didn't post it.
printf("Enter the grade that you want to remove. Press Enter after each input.");
printf("Enter 0 to exit: ");
[Code] ....
I didn't mean to leave the "prototyping" part in the code. I was initially going to put the function prototypes in there, but decided it wasn't necessary for the question.
When the program is processing/sleeping, those char input at that time would not goes into the buffer until the next input request (such as calling istream::get). The program below shows this.
#include <iostream>
#include <streambuf>
#include <chrono>
#include <thread>
int main() {
std::cout << "Sleeping...
[Code] ....
I wonder if there is a way to distinguish between the input comes from the time that does not request it (i.e., during processing or sleeping) and those comes after the time does request it (in the example, after "Input something: ").
I plan to read one character at a time from a very large text file.
The tokens that I would like to extract are basically words and they are delimited by varying numbers of spaces or tabs.
For example, the first line has two words separated by five spaces:
Joe Mark
Problem:I apply get() each time advancing towards Mark. For me to know ive reached the next token, Mark, I merely have to get() until it equals 'M'. The problem by then its too late as Ive already captured 'M'. I somehow need to capture the fifth space and the code must "know" the next character is 'M' without getting() it.
Kernighan and Richie offer us a function getch() and ungetch() whereby the ungetch pushes back the last character into the input . The problem with this is that I believe is that the buffer is not the actual input buffer stream but rather a simulated character array which contains the input. I dont think itll be as efficient on a text file so large.
The documentation of the class filebuf in the reference of cplusplus.com says:
Objects of this class may internally maintain an intermediate input buffer and/or an intermediate output buffer, where individual characters are read or written by i/o operations. These buffers are synchronized with the contents of the file once filled up, when explicitly requested to do so (sync), or when the object is closed.
Objects of this class may be explicitly made unbuffered by calling member pubsetbuf with both arguments set to zero (see member setbuf): Unbuffered file stream buffers perform the i/o operations directly on the file, without an intermediate buffer.
The C++ standard ensures that filebuf objects have an intermediate input/output buffer/s (i.e, the default constructor of the class filebuf creates the intermediate buffer/s)?
The standard C++ library only allows unbuffering filebuf objects (as the above quote says) but doesn't allow forcing filebuf objects to be buffered.
I have been seeying the concrete implementation code of the standard C++ library in my Windows Operating System (Windows 7 Ultimate 64 bits Service Pack 1) and it seems that fielbuf objects never uses intermediate input/output buffer/s, they use FILE streams of the standard C library instead to do the work. Are this FILE streams always buffered? If true, are they fully-buffered or line-buffered? what is the size of the buffers (perhaps macro BUFSIZ from <cstdio>)? and can I change this size?
I am worried about performance in reading and writing from/to files: if the default behaviour offers the best performance (perhaps if files are too large is better force buffering and choose a larger buffer size).
I am writing a program and am asking the user to enter a number between 1-12.
If they do not, they will be promoted over and over again to enter a number between 1-12.
However, if the user enters a letter or anything else scanf seems to stop working and then my loop goes out of control.
Using cin.sync() works great so far, but my program still breaks if you copy something with multiple lines into the console.
string test = "";
while(true) {
cin.sync();
getline(cin, test );
cout << endl << "test: " << test << endl;
}
However, if you were to copy this:
1
2
3
and paste it into the program, the output would be1
2
3
test: 1
test: 2
And if you press enter one more time:1
2
3
test: 1
test: 2
test: 3
The 3 finally pops out.
I am trying to create a simple interface on console to allow to input some values to some variables. For ex:
int main() {
double a = 1.5;
double b = 2.5;
double c = 3.5;
string x;
[Code] ....
However, I want these three to display at the same time (now they display one by one), and in the console window I can move the cursor between input place of a, b and c with "arrow key" of keyboard.
deal with a failed input stream and type checking input?
I use:
cout << "
Enter a menu option: ";
while(!(cin >> menuGameMode))
{
cin.clear();
while (cin.get() != '
')
continue;
cout << "Enter a menu option: ";
}
Is this the "Best" way to do it?
EDIT: We're assuming input is expecting an int.
Program is to add two fractions together like so..
This program adds fractions. ‘Y’ continues, any other key exits program
===================================================
Enter numerator 1 ==> 1
Enter denominator 1 ==> 3
Enter numerator 2 ==> 1
Enter denominator 2 ==> 6
1 1 1
--- + --- = ---
3 6 2
-----------------------------------------------------
Continue? Y or N! ==> n
My question is that i need each input to be a number.
if a character is entered i want it to output something like..
This program adds fractions. ‘Y’ continues, any other key exits program
===================================================
Enter numerator 1 ==> 1
Enter denominator 1 ==> a
You need to enter a number here.
Press any key to continue.
and then clear the part where the letter was entered.
This program adds fractions. ‘Y’ continues, any other key exits program
===================================================
Enter numerator 1 ==> 1
Enter denominator 1 ==>
This is for homework . Must use only getchar and putchar
Code:
int main(void) {
int pch; //first
int ch; //second
[Code]....
And it works , but i need to hit ENTER two times when i have 3,5,7... chars to print result.
I need to get an integer number with only using getchar() and without pre knowing the number of digits in the integer. And I cannot use strings or arrays.
View 4 Replies View RelatedI basically just have to make a calculator that only uses getchar/putchar (printf is Ok for displaying errors) - Also, negatives must be error-checked. As of right now, my program will only work if there is exactly one space between the number, operand, and other number. No spaces, or more than one space, will give me some very weird digits. I also need to display the numbers with putchar, and not printf (as I did below), but I just really wanted a working program.
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
int add(int input1,char operand, int input2);
int subtract(int input1,char operand, int input2);
[Code] .....
Once again i hit a very simple problem i am unable to resolve. I using Visual Studio 2010, but am compiling for C.
This:
Code:
char i=45;
while(i=getchar() != EOF)
{
should imo work perfectly (yes, no real code, just to demonstrate the issue), but it doesnt. Getchar() always returns 0x01. Why is that? This, in contrast, works perfectly fine:
Code:
char i=45;
while(i!= EOF)
{
i=getchar();
Shouldnt an assignment always return the assigned value?
I have to make a calculator program that has 5 different functions (this is obviously the easy part, once all the input is assigned to their respective variables), which are addition, subtraction, mod, multiplication and division (negatives are not allowed, and must be error-checked; spaces must be ignored). I need to take the equation from the user, echo it back and then solve the problem.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
[Code].....
here is a nested stl map
typedef struct struct_RISCP {
float nSCPTotal;
int nSCPCount;
CString strIMEI;
std::map<UINT8, int> mapSection;
}RISCPSt;
map<stRncCellIdntyDmnType, RISCPSt>m_mapRISCP;
it occupied too much memory,i wanted to clear them(both outer map and inner map) ,some one told me you just need to call m_mapRISCP.clear(),then the mapSection (inner map) will be cleared automaticly,in other words, m_mapRISCP.clear() will clear both outer map and inner map.
I have a one simple question :D. I want to output to the console some symbols. Let's say that i have a loop.
for(int i = 0; i < 10; i++) cou << "* ";
Then I want to output other symbols but I want to overwrite the previous symbols. I know I can use system("cls"); but it blinks if I try to output the same characters. For example if I have:
for(int i = 0; i < 10; i++) cou << "* ";
system("cls");
for(int i = 0; i < 10; i++) cou << "* ";
After I run this code the first loop outputs ten "*". Then there is a blink and there are again ten "*" shown. How can I avoid this blink?
vector<int> *vec; allocate memory and
suppose vec conatins 10 values then
erase(vec->begin(),vec->end());
vec.clear();
both should be used or any one one is fine to erase all ??
Is there any way I can clear only a selected part of the screen? (I'm aware of system("cls"))
For example, when you enter a date, and is wrong, could it just errase that input and only say "Wrong try again" without errasing everything else you where doing?
In this case, a function that only errases what is in the while
while(not wrong)
{
cout<<"DIA: ";
cin>>obj.dia;
cout<<"MES: ";
cin>>obj.mes;
cout<<"ANIO: ";
cin>>obj.anio;
}
PS: Also, is there any whay in which you can ask the user to enter the date DD/MM/YYY?