Reading ASCII numbers using “D” instead of “E” for scientific notation using C

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执笔经年
执笔经年 2020-12-21 21:33

I have a list of numbers which looks like this: 1.234D+1 or 1.234D-02. I want to read the file using C. The function atof will merely

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  •  轮回少年
    2020-12-21 22:07

    You can take advantage of strtod and strtok:

    #include 
    #include 
    #include 
    
    int main(void) {
        char in[] = "1.234D+1 ABCD 1.234D-02 5\n";
        char *cursor;
        char *endp;
        for ( cursor = strtok(in, " "); cursor; cursor = strtok(NULL, " ")) {
            double d = strtod(cursor, &endp);
            if ( *endp == 'D' ) {
                *endp = 'e';
                d = strtod(cursor, &endp);
            }
            if ( endp != cursor ) {
                printf("%e\n", d);
            }
        }
        return 0;
    }
    

    Output:

    E:\> cnv
    1.234000e+001
    1.234000e-002
    5.000000e+000

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