<iostream> <stdio.h>

This is a discussion on <iostream> <stdio.h> within the C++ Programming forums, part of the General Programming Boards category; What is the difference between #include <iostrream> and <stdio.h>?? we have began lessons on c++ programming in school and we ...

  1. #1
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    Question <iostream> <stdio.h>

    What is the difference between #include <iostrream> and <stdio.h>??

    we have began lessons on c++ programming in school and we are being taught in #include<stdio.h> and w/o "using namespace std;" and there are different codes like printf which is also cout and others..
    is one better than the other?

    and well, i don't even know what #include<****> are for..

  2. #2
    Frequently Quite Prolix dwks's Avatar
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    stdio.h is a C header file for basic C functions like printf(). iostream is a C++ header file for basic I/O, like cout. (To use stdio.h in C++, use cstdio.) iostream.h is an older version of iostream. Standard C++ header files don't have a .h extension.

    [edit]
    and well, i don't even know what #include<****> are for..
    They have prototypes so the compiler can tell you're passing the right arguments to functions; classes so you can create instances of them; #defines so you can use constants; etc.
    [/edit]
    dwk

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    thank you..

    but is one of them better than the other?

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    First, what the pre-compiler command #include does is simple: it pastes the content of the file specified either between " " or < >. Second, you should use cstdio over stdio.h because the latter is not standard. Third, the difference is simple, cstdio provides C-style input/output functions/structs and others while iostream provide C++ input/output functions and classes. I would generally stick to iostream when programming in C++ but I have found lately that sometimes it's better to use the good old C functions. Sometimes they are more convenient and sometimes not. It's up to you.

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    I like the iostream stuff better, because the syntax is simpler.

  6. #6
    Frequently Quite Prolix dwks's Avatar
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    Plus it's more extensible. (You can write your own operator<<() and cout your objects.) If you program in C++ you should use the iostream library.
    dwk

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    >> Second, you should use cstdio over stdio.h because the latter is not standard.
    This isn't accurate. Both stdio.h and cstdio are standard in C++, it is just that stdio.h is deprecated in favor of cstdio.

    Besides, iostream should be preferred because it works with classes in C++.

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    In some cases, using streams is just more work for nothing:

    Code:
    std::cout << "Hi " << userName << " it is now " << hours << ':' << mins << ':' << secs << " and you are the " << rank << " user." << std::endl;
    printf("Hi %s, it is now %d:%d:%d and you are the %d user", userName, hours, mins, secs, rank);

  9. #9
    and the hat of wrongness Salem's Avatar
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    > In some cases, using streams is just more work for nothing:
    You mean replacing a conversion checked at compile time (C++) for an unchecked conversion at run time (C)
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    Look on the bright side: in my MinGW compiler, an <iostream> "Hello World" program is 250 KB, a <stdio.h> one is only six.

    Too much inheritance can be a bad thing
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

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    These days, 250kb is a negligible amount of space - especially for a Hello World program. The power of OOP is mainly for larger programs, and is generally aimed at making program easier, not more space-efficient. If space and performance is of major concern, I can see your point, but for mainstream programming, iostream makes the job A LOT easier.

  12. #12
    C++ Witch laserlight's Avatar
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    Look on the bright side: in my MinGW compiler, an <iostream> "Hello World" program is 250 KB, a <stdio.h> one is only six.
    Perhaps you should read what the MinGW FAQ and Stroustrup's FAQ has to say about that.
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  13. #13
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    Quote:
    Look on the bright side: in my MinGW compiler, an <iostream> "Hello World" program is 250 KB, a <stdio.h> one is only six.

    How is that?

  14. #14
    erstwhile
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    >>How is that?<<

    If by 'how' you mean 'why' then it's for two reasons. Firstly the respective parts of the stl are statically linked and secondly because a lot of symbolic debug information is included in the built executable (this may be explained in the MinGW faq referred to by laserlight). In the first case, the size hit is only for the first inclusion; subsequent uses will not significantly add to bloat. For the second case, link with the -s (strip) option.

    You can also build and use stlport for MinGW and dynamically link with that implementation of the standard library; you'll probably want to use something like that if your require wide character support anyway; beyond std::wstring, MinGW's stl implementation has little wide character support. Executables dynamically linked with stlport's standard library give sizes comparable to those built using cstdio/stdio.h and for pretty much the same reason - dynamic linkage of the relevant libraries. An '<iostream> hello world' program is ~20kb with stlport(v5.0) with MinGW (stripped, ie, -s linker switch).
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