Question

While looking at some conceptual questions in C,I came across this question in a book. What is the output of the following program ?

#include<stdio.h>
#include<string.h>
int main()
{
    static char s[25]="The cocaine man";
    int i=0;
    char ch;
    ch=s[++i];
    printf("%c",ch);
    ch=s[i++];
    printf("%c",ch);
    ch=i++[s];
    printf("%c",ch);
    ch= ++i[s];
    printf("%c
",ch);
    return 0;
}

答复:

 hhe!

谁能解释这一产出如何?

Answer 1

从第一次转让开始

ch=s[++i];

编号I(i=1)和编号ch。

ch=[i++];

分配<代码>ch ,以<代码>(i=1)为特征,然后加插(i=2)。

<>代码>ch=i++[s];

分配<代码>ch , 特性为<代码>(i=2)>,然后加插(i=3)。关键:[i] == i[s]。

ch> ++i[s];

将ASCII数值按()的指数(i=3)重新计算,并将其分配到ch。关键:[ ] 高于序号<>++>>

Answer 2

了解这一点的关键是,在C,以下各点是:

x[y]
*(x+y)

and also that prefix ++ has lower precedence than [].

A table of the ASCII character set will also come in handy.

Answer 3

first of all i=0, now for s[++i], i=1 and s[1] will give h.
现在请上<代码>[i++],并注明<编码> > ***,即<代码>h,i为2。
<代码>i++[s],我们必须知道,i[s]=s[i]。现在,它将提供<条码>第2条,即<条码>e>和i=3值。
Now for the most important part ++i[s], we can think of it as ++(i[s]) because [ ] operator has greater precedence than ++. Since i[s] is a char value, ++ operator will work on its ASCII value that is ASCII value of s[3] i.e (Space) which is 32 http://www.asciitable.com/ . 32 is incremented by 1 and becomes 33 which is ASCII value of !.

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