1.2 Variable definition, assignment and conversion of programming basics

portal:http://noi.openjudge.cn/ch0102/

A set of water problems, but they are still the problem

01-03 is the basic data type storage space size

01

#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {int  A;  Short b;cout<<sizeof(a) <<'<<sizeof(b) ;     return 0 ;}

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02

#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {float  A; Double b;cout<<sizeof(a) <<'<<sizeof(b) ;     return 0 ;}

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03

#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {char  A; BOOL b;cout<<sizeof(a) <<'<<sizeof(b) ;     return 0 ;}

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Well, in fact, sizeof () is a relatively unpopular in OI statement, but in the measurement of the space consumption of the topic is useful

The next time you encounter an SB problem, use it to measure the space.

That's right

Basic data type storage space size

BOOL 1 (bytes)

Char 2

Short 2

int 4

Long 4

Float 4

Double 8

Long Double 16

Long Long 8

So what can we learn from it?

What I understand is:

1. Wretched to use bool and char (+hash? ) store 255 or less of the data

2. Up to 300W for 256MiB space array

Up to 80W for 65536KB spatial arrays (various basic data structures)

3. Do not set a map,map in the vector and set a pair and a queue, do not do the big constant Master

04 05: ... you're teasing me. answer questions in a variety of ways

#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {cout<<'D'<<'<<' C ' ;     return 0 ;}

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#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {cout<<'F'<<'<<' E ' ;     return 0 ;}

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06 07 08 09: Forced type Conversion

Format has (type specifier) (expression), type specifier ((expression)), etc.

#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {float  A; int b;cin>>a;b=a;cout<<b;     return 0 ;}

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#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {char  A; int b;cin>>a;b=a;cout<<b;     return 0 ;}

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#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {int  A; Char b;cin>>a;b=a;cout<<b;     return 0 ;}

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#include <iostream>#include<cstring>#include<cstdio>using  namespace  std; int Main () {int  A; BOOL b;cin>>a;b=a;a=b;cout<<A;     return 0 ;}

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10: Hehe "Hello, the size of world!" This question is also can

#include <iostream>#include<cstring>#include<cstdio>int  main () {    printf ("%d",sizeof("Hello, world! " ));     return 0 ;}

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Overall: Although water, but very good, these questions are not focus on practice and results, but to guide students to "explore" C + + language usage and standards

I have to say, CCF did a good deed.

1.2 Variable definition, assignment and conversion of programming basics