What does this arrow in cmd mean - c

I'm writing a program which takes input and outputs it one word per line.
#include <stdio.h>
int main()
{
int c;
while( (c = getchar()) != EOF)
{
if( c != ' ')
putchar(c);
else
putchar('\n');
}
}
The program stops when it encounters the EOF character. When I input something like "Hello World^Z" (I am using Windows) I get the following output:
C:\Coding\C>a
Hello World^Z
Hello
World→
And it still waits for me to input something. What does the → symbol mean?

Related

C code doesn't print whole paragraph with newlines

This is my C code:
#include <stdio.h>
int main()
{
int c = getchar();
while (c != EOF) {
if (c != '\n')
putchar(c);
else putchar(32);
c = getchar();
}
return 0;
}
I want to make a program that prints out a paragraph with newlines, by replacing the \n character with spaces. The problem is, it only prints out the last line, when I use the code provided above.
For, example, for the text:
This is
my
text
the result printed is text.
The paragraph is properly printed when I remove the if(), else conditions, and only leave the putchar(), without trying to replace anything.
What's the problem?
Your input file has CRLF newlines. You need to ignore the CR characters when you're replacing LF with space. Otherwise, printing the CR characters will go back to the beginning of the line and overwrite what was already printed.
#include <stdio.h>
int main()
{
int c;
while ((c = getchar()) != EOF) {
if (c == '\n') {
// replace newline with space
putchar(' ');
} else if (c == '\r') {
// ignore CR
} else {
putchar(c);
}
}
return 0;
}

getchar() stuck in a loop never reaching the EOF

#include <stdio.h>
int main() {
int c;
while(getchar() != EOF) {
if (getchar() == ' ') {
c++;
}
printf("%i", c);
}
}
I realized that typing in a sentence like the one you're reading right
I\nrealized\nthat\ntyping\nin\n\a\n ...
i believe that's how it's being read, getchar() does not reach the EOF to make the condition in the while parentheses false..
my goal here is to make a program that takes in input from me..
reads it
if there are any spaces
it counts on a counter
when EOF is reached
the condition to keep reading it becomes false
the counter value gets printed out on the screen
to show me how many spaces i had in my entire input..
is it impossible? is that why people just use scanf() ?
this is the output i get when trying something
user#user:/c# ./a.out
hello stackoverflow this does not do what i want it to
001111111222223344445666677
You need to put the result of getchar() into a variable:
int ch;
while ((ch = getchar()) != EOF)
You shouldn't call getchar() a second time to check if it's a space, since that will read a second character so you'll be testing every other character, just compare the variable:
if (ch == ' ')
And if you want to see the total number of spaces, put the printf() at the end of the loop, not inside it.
So the whole thing should look like:
#include <stdio.h>
int main() {
int counter=0;
int ch;
while((ch = getchar()) != EOF) {
if (ch == ' ') {
counter++;
}
}
printf("%i\n", counter);
}
To send EOF from the terminal, type Control-d on Unix, Control-z on Windows.

How to give input to compiled C program on Mac from terminal

I am trying to solve an assignment question - "Write a program to copy its input to its output, replacing each string of one or more blanks by a single blank". After writing the code, I am trying to compile it on a Mac terminal. I know how to compile using gcc command.
How do I give input from terminal to see what the output is?
The code that I have tried:
#include <stdio.h>
int main(void)
{
int c, inspace;
inspace = 0;
while((c = getchar()) != EOF)
{
if(c == ' ')
{
if(inspace ==0)
{
inspace = 1;
putchar(c);
}
}
if(c != ' ')
{
inspace = 0;
putchar(c);
}
}
return 0;
}
Use
gcc program.c
then run using :
./a.out
don't give enter, first type in some characters using your keyboard, then press enter. You'd need to type control-D at the beginning of a line to indicate EOF (or type it twice to indicate EOF without a newline as the last character). You could also interrupt the program with control-C.

printing a word per line

I need to write a program that prints its input one word per line. Here's what I got so far:
#include <stdio.h>
main(){
int c;
while ((c = getchar()) != EOF){
if (c != ' ' || c!='\n' || c!='\t')
printf("%c", c);
else
printf("\n");
}
}
The logic is pretty simple. I check to see if the input is not a newline, tab or space, and in that case it prints it, otherwise prints a newline.
When I run it, I get results like this:
input--> This is
output--> This is
It prints the whole thing. What goes wrong here?
if (c != ' ' || c!='\n' || c!='\t')
This will never be false.
Perhaps you meant:
if (c != ' ' && c!='\n' && c!='\t')
instead of using printf try putchar, also as per above comments, you should use && instead of ||.
here is my code-
#include<stdio.h>
main()
{
int c, nw; /* nw for word & c for character*/
while ( ( c = getchar() ) != EOF ){
if ( c != ' ' && c != '\n' && c != '\t')
nw = c;
else {
nw = '\n';
}
putchar (nw);
}
}
this code will give you the desired output
you can use if you want the strtok function in string.h library which can cut the input into many words by providing a delimiter.
Here is a perfect code commented which can fit to your needs
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
char line[1000]=""; // the line that you will enter in the input
printf("Input the line:\n>>");
scanf("%[^\n]",line); // read the line till the you hit enter button
char *p=strtok(line," !#$%&'()*+,-./'"); // cut the line into words
// delimiter here are punctuation characters (blank)!#$%&'()*+,-./'
printf("\nThese are the words written in the line :\n");
printf("----------------------------------------\n");
while (p!=NULL) // a loop to extract the words one by one
{
printf("%s\n",p); // print each word
p=strtok(NULL," !#$%&'()*+,-./'"); // repeat till p is null
}
return 0;
}
If we execute the code above we will get
Input the line:
>>hello every body how are you !
These are the words written in the line :
----------------------------------------
hello
every
body
how
are
you
suggest the code implement a state machine,
where there are two states, in-a-word and not-in-a-word.
Also, there are numerous other characters that could be read
(I.E. ',' '.' '?' etc) that need to be check for.
the general logic:
state = not-in-a-word
output '\n'
get first char
loop until eof
if char is in range a...z or in range A...Z
then
output char
state = in-a-word
else if state == in-a-word
then
output '\n'
state = not-in-a-word
else
do nothing
end if
get next char
end loop
output '\n'
I think the simple solution would be like
#include <stdio.h>
int main(void) {
// your code goes here
int c;
while((c=getchar())!=EOF)
{
if(c==' ' || c=='\t' || c=='\b')
{
printf("\n");
while(c==' ' || c=='\t' || c=='\b')
c=getchar();
}
if(c!=EOF)
putchar(c);
}
return 0;
}

echoing of getchar and '\n' char from stdin

I have already looked at this similar question but i am still wondering if there is another way to stop 1) the terminal echoing with portabilty as this is an assignment and I have already had one java program crash and burn on my teachers computer 2) in my program i search for a '\n' char then if it isn't the first char use getchar then putchar till the next '\n' char which works fine when using redirected stdin but when I try using the program without redirection the enter key is always echoed, is this to do with the terminal echoing or do i need to check for a diffrent char apart from '\n'? I have also tried including '/r' and done lots of googling but it seems the answer to the echo is can't be done with portabilty?
#include <stdio.h>
#include <string.h>
int first_line(char);
int main(){
char c;
while((c = getchar())!=EOF){
first_line(c);
}
return 0;
}
int first_line(char c){
if (c != '\n'||c != '\r'){
putchar(c);
do{
c = getchar();
putchar(c);}
while( c !='\n');
}
return 0;
}
Thanks Lachlan
For a start try with the following :
1) the condition should be if (c != '\n' && c != '\r')
2) and the while loop ,in case if terminal is line buffered then you are better of using getchfrom ncurses library the library packages should be there for most platforms.
while((c =getchar())!='\n') {
putchar(c);
}

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