Rules to compare two strings object

In my book I have the following example :

Code:

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    std::string str = "Hello";
    std::string phrase = "Hello world";
    std::string slang = "Hiya";

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and i have these two rules to compare 2 strings object :

if two strings have different lenghts and if every character in the shorter string is equal to the corresponding character
of the longer string, than the shorter string is less than the longer string.

if any characters at corresponding positions of two strings differ, then the result of the string comparision is the result
of comparing the first character at wich the strings differ

then my book says : if we apply the rules of the comparision we know that phrase is greater than str( ok i've understood this ) and that slang is greater than both slang and phrase ( why ?? )

could you exolain me rule number two ? in phrase and slang the characters differ and the first character that differ is not H so why my book says slang is bigger than phrase ?

I think you made a typo error, i.e., "slang is greater than both slang and phrase" should be "slang is greater than both str and phrase".

Consider str and slang: their lengths are different, and not "every character in the shorter string is equal to the corresponding character of the longer string", hence we apply the second rule. The first character at which the strings differ are the characters at index 1, i.e., 'e' for str and 'i' for slang. Assuming ASCII or some other character set in which the letters of the English alphabet have values in their canonical order, 'e' < 'i', hence str < slang. Likewise for phrase and slang.

Quote:

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Originally Posted by laserlight

I think you made a typo error, i.e., "slang is greater than both slang and phrase" should be "slang is greater than both str and phrase".

Consider str and slang: their lengths are different, and not "every character in the shorter string is equal to the corresponding character of the longer string", hence we apply the second rule. The first character at which the strings differ are the characters at index 1, i.e., 'e' for str and 'i' for slang. Assuming ASCII or some other character set in which the letters of the English alphabet have values in their canonical order, 'e' < 'i', hence str < slang. Likewise for phrase and slang.

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so i should the compare the characters of two strings object ? why if i change the value of str to "Hhllo" str is not greater than slang ? 'h' is bigger than 'i' right ?

Quote:

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Originally Posted by piero borrelli

so i should the compare the characters of two strings object ?

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Yes.

Quote:

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Originally Posted by piero borrelli

why if i change the value of str to "Hhllo" str is not greater than slang ? 'h' is bigger than 'i' right ?

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Compile and run this program to find out:

Code:

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#include <iostream>

int main()
{
    std::cout << static_cast<int>('h') << ' ' << static_cast<int>('i') << std::endl;
}

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