求助！！！

[Foresee]

读入若干字符行，以空行（即只键入回车符的行）结束，输出其中最长的行。

[bdmh]

while循环呗

[Foresee]

以空行（即只键入回车符的行）结束 这个怎么实现

[Foresee]

[Quote=引用 1 楼 bdmh 的回复:]
while循环呗
[/Quote]能不能详细点，最好给出程序

[Viking_Mei]

getline(cin, str)
然后判断str是否为空即可

#include <string>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    string str;
    string maxStr;

    long index = 0;

    cout << "Please input strings to test, seperate with Enter:\n" << index++ << "\t";

    while ( getline(cin, str) ) {
        // whether have input a empty line 
        if (str.empty()) {
            break;
        }

        cout << index++ << "\t";

        if ( str.length()>maxStr.length()) {
            maxStr = str;
        }
    }
    
    if (maxStr.empty()) {
        cout << "\nSorry, you have not input any string!\n";
    }
    else {
        cout << "\nThe longest string is: " << maxStr << endl;
    }

    return 0;
}

[qq120848369]

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
        char line[100];
        int max_chars = 0;

        // fgets can be finished with ctrl+D as well.
        while (fgets(line, 100, stdin) != NULL)
        {
                // enter only
                if (line[0] == '\n')
                {
                        break;
                }

                printf("%s", line);

                int line_chars = strlen(line) - 1;

                if (line_chars > max_chars)
                {
                        max_chars = line_chars;
                }
        }

        printf("max_chars : %d \n", max_chars);

        return 0;
}

[herocxgood]

char p[30]="abc";
char pt[40]="";
cout<<"please input the string:";
while(p[0])
{
//cin.getline(p,30);
if( strlen(p)>strlen(pt))
{
strcpy(pt,p);
}
//strcpy(p,"");
cin.getline(p,30);
}
cout<<"the longest string is:";
cout<<pt<<endl;
我对c++也刚开始学习，上面功能很简单