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printf( "%g", 1.2 ); // 1.2
printf( "%g", 122222222.2 ); // 1.22222e8
printf( "%G", 122222222.2 ); // 1.22222E8
printf("%g",4.5);//4.5
printf("%f",4.5);//4.500000
printf("%e",400.5);//4.5e+2