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StringPrintf: A Typesafe printf Family for C++


August, 2005: StringPrintf: A Typesafe printf Family for C++

Listing 1

int main()

{   string s1;
    const short          i1 = -12;
    const unsigned short u1 =  23;
    const float          f1 = 3572.24f;
    const double         d1 = -237E-12;
    const char *        cp1 = "submarine";

    // printf-style function
    // correct string and output
    StringPrintfCout("int = %d%%; float = %3.1f\n\n", i1, f1);
    // Outputs: "int = -12%; float = 3572.2"

    // Use Wrong Types
    StringPrintfCout("string = %s; int = %3d\n\n", f1, i1);
    // Outputs: "string = 3572.247070; int = -12"

    // sprintf-style function
    // Too few Arguments
    StringPrintf(s1, "string = %s; int = %3d, %s, %d, %s", f1, d1);
    cout << s1 << "\n\n";
    // Outputs: "string = 3572.247070; int = -0.000000, %s, %d, %s"

    // Too many Arguments
    StringPrintf(s1, "string = %s; int = %3d", cp1, f1, d1, u1);
    cout << s1 << "\n\n";
    // Outputs: "string = submarine; int = 3572.247070"

    // User defined Type
    myUserClass User1;
    StringPrintf(s1, "User1 = %s", User1);
    cout << s1 << "\n\n";
    // Outputs: "User1 = userClassValue"
    // fprintf-style function
    FILE *file;
    if(file = fopen("test.txt", "w"))
    {
        StringPrintf(file, "string = %f; int = %3d\n", f1, i1);
        // Outputs to file: "string = 3572.239990; int = -0.000000"
        fclose(file);
    }
    // Dangerous! sprintf-style buffer overflow possible
    char buff[100];
    StringPrintfCout("int = %d%%; float = %3.1f\n\n", i1, f1);
    // Outputs: "int = -12%; float = 3572.2"

    // snprintf-style function using buffer length parameter 
#define BUFFLEN 24
    char tx[BUFFLEN];
    StringPrintf(tx,BUFFLEN,"String = %s; float = %f,double = %f",cp1,f1,d1);
    tx[BUFFLEN - 1] = 0;
    cout << tx << "\n\n";
    // Outputs: "String = submarine; flo"

    return 0;
}


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