2021-10-18 character array

1.

 

Read a set of text lines from the terminal , And print the longest line of text

      Code ：

#define MAXLINE 1000

int getline(char line[],int maxline);
void copy(char to[],char from[]);
main()
{
    int len;
    int max;
    char line[MAXLINE];
    char longest[MAXLINE];
    
    max=0;
    while((len = getline(line,MAXLINE))>0)
        if (len > max){
        max = len;
        copy(longest,line);
        }
    if (max = 0)
        printf("%s",longest);
}
int getline(char s[],int lim)
{
    int c,i;
    
    for (i=0;i<lim-1&&c!='\n'&(c=getchar())!=EOF;i++)
        s[i] = c;
    if(c=='\n'){
        s[i] = '\n';
        i++;
    }
    s[i] = '\0';
    return i;
}
void copy(char to[],char from[])
{
    int i;
    
    i = 0;
    while((to[i] = from[i]) != '\0')
        ++i;
}
 

     

      analysis ：

     1,   Two data structures are required ：line,longest Save the current input line , The longest line ,line longest All points to a size of MAXLINE Of char Array .

     2,  getline function ： Read a line into line in , Return its length .

          (a)：for The judgment condition of cycle ,i < lim-1 && (c = getchar()) != EOF && c != '/n', When these conditions are met , Read in... From the terminal

                  Put characters in s Array ( Argument line Array ) in .

          (b)：Q： Why not i <= lim-1 Well ？ A： The end of the string must be '/0', If set to i <= lim-1, In this case i <= 999,

                  If a string happens to be 1000 Characters , When reading the first 1000 In characters , And the character is not '/n', It didn't reach the end of the file , It's in line with for

                  The judgment condition of cycle , perform s[i] = c;, At this point, the character array s( Corresponding arguments line) It's full of , When jumping out of the loop, execute s[i] = '/0'; when , because

                  Space is not enough , An out of bounds error has occurred .

          (c)： When read in '/n' when , It means that the operation of reading a line of characters from the input is about to be completed , What needs to be done at this time is to '/n' and '/0' Put in s[i] in .

          (d)： When the read character is EOF, Means the end of the file is reached , There are no more characters to read in the input , So Zaijiang /0' Read in to s in , To form a string ,

                  This string is stored in a character array s in .
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