Convert string to float?

This is a discussion on Convert string to float? within the C++ Programming forums, part of the General Programming Boards category; I've got two floats but they're as strings. how do i get this code to work. I don't know how ...

  1. #1
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    Convert string to float?

    I've got two floats but they're as strings. how do i get this code to work. I don't know how to convert them so i can compare them. it's read from standard input that's why they're char*. The code below is just an example, i know it's not goin2 work lol. Please tell me how to convert so i can compare, thanx

    Code:
    char* f1 = 3.2;
    char* f2 = 4.53;
    
    if(f1 > f2) {
    
    cout << "F1 is bigger" <<endl;
    
    }else {
    
    cout <<F2 is bigger" <<endl;
    
    }

  2. #2
    and the hat of wrongness Salem's Avatar
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    strtod()
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  3. #3
    and the hat of sweating
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    Since this is C++, not C, you should use a std::stringstream
    Code:
    std::stringstream ss;
    std::string str = "3.14";
    float f = 0.0f;
    ss << str;
    ss >> f;
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    C++ Witch laserlight's Avatar
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    Moved to C++ programming forum.
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    You can try boost::lexical_cast which is powerful & convenient.

    lexical_cast

  6. #6
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    Hi,

    You can use the method atof() to implement it!

    #include <stdlib.h>


    char* f1 = 3.2;
    char* f2 = 4.53;

    int a, b;
    a = atof(f1);
    b = atof(f2);

    Carle
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  7. #7
    ...and never returned. StainedBlue's Avatar
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    Quote Originally Posted by carle View Post
    Hi,

    You can use the method atof() to implement it!

    #include <stdlib.h>


    char* f1 = 3.2;
    char* f2 = 4.53;

    int a, b;
    a = atof(f1);
    b = atof(f2);

    Carle
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    No. atof() is also C. The stringstream idea is C++.
    goto( comeFrom() );

  8. #8
    C++まいる!Cをこわせ! Elysia's Avatar
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    Would do you gain from trying to assign a floating number to a char pointer?
    Answer: nothing. Do not even attempt it.
    Quote Originally Posted by Adak View Post
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    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

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