Basic questions about C

Hi

I was going threw a book learning about C language and I had a few questions if someone could help me out to clarify a few things.

Float or double….why is one better than the other? From what I understand the double is more precise than the float. If that is so why use the float?

What is the difference between getc and getchar? Aren’t they basically the same thing?

What is the difference between putc and putchar? The only difference I see is that putc requires that you use the variable name and stdout “ putc(variable_name, stdout) “ and putchar only requires the variable name “ putchar( variable_name) “ . Is that the only difference? If so then what is the purpose of “putc”?


Precision specifier question. When I run the program the integer 17 will print out 017 which I understand, and the 11.7 will print out 11.700, and I understand the .700, but I don’t quit understand the purpose of the -3. what is its purpose. Isn’t the “-“ simply a left specification? I would have thought that 11.7 would have appeared as 011.700. What is the purpose of the number 3 after the negative sign in the second print statement?
printf("%.3d\n", 17);
printf("%-3.3f\n", 11.7);

Quote:

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Originally Posted by FlatLost

Hi

I was going threw a book learning about C language and I had a few questions if someone could help me out to clarify a few things.

Float or double….why is one better than the other? From what I understand the double is more precise than the float. If that is so why use the float?

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If you can do with less precision then why to go for double....un-necessary wastage of memory

Quote:

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Originally Posted by FlatLost

What is the difference between getc and getchar? Aren’t they basically the same thing?

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You can specify the stream from which you can take the input in getc whereas getchar gets a character from stdin (default)

Syntax of getc

Code:

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int getc( FILE *stream );

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Syntax of getchar

Code:

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int getchar( void );

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Quote:

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Originally Posted by FlatLost

What is the difference between putc and putchar? The only difference I see is that putc requires that you use the variable name and stdout “ putc(variable_name, stdout) “ and putchar only requires the variable name “ putchar( variable_name) “ . Is that the only difference? If so then what is the purpose of “putc”?

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Same as above but instead of reading it writes

Quote:

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Originally Posted by FlatLost

What is the purpose of the number 3 after the negative sign in the second print statement?
printf("%.3d\n", 17);
printf("%-3.3f\n", 11.7);

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It tells the number of decimal points in which you want your answer...that is why its coming out to be .700. if you would not have mentioned .3 then the output would have been 11.700000(default precision of float 6 decimal places)

It tells the number of decimal points in which you want your answer...that is why its coming out to be .700. if you would not have mentioned .3 then the output would have been 11.700000(default precision of float 6 decimal places)

Thanks for the help sunnypalsingh.

I understand what you are saying about the .3 and that the .3 is the number of decimal points in which the answer will come out to, but what about that first 3 behind the '-' sign. what is its purpose?

printf("%-3.3f\n", 11.7);

run this little program and you will easily see what the '-' symbol does. It left-justifies the number in the field.

Code:

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int main(int argc, char* argv[])
{

printf("%-15.3fHello World\n", 1.72132);       
printf("%15.3fHello World\n", 1.72132);       
       
        return 0;
}

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Quote:

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Originally Posted by FlatLost

I understand what you are saying about the .3 and that the .3 is the number of decimal points in which the answer will come out to, but what about that first 3 behind the '-' sign. what is its purpose?
printf("%-3.3f\n", 11.7);

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'-' sign signifies that the output will be left justified.....by default it is right justified..

%w.p type specifier

where w is an integer number that specifies the total number of columns for the output value(including the decimal point .) and p is another integer number that specifies the number of digits to the right of the decimal point(of real number)

next time use tags

Thanks Ancient Dragon that little code sample really helped make things clear. Again thanks to sunnypalsingh as well for clearing things up for me!