C # "pitfalls" of float and double"

Define a float type variable = 0.7, but the result is 0.69999999 in Il.

Multiply by 10 to obtain the integer. The result is 6. By checking the Il, it is converted to the double type before conversion. It becomes 6.

Demo:

Il:

. Method private hidebysig static void main (string [] ARGs) cel managed {. entrypoint // code size 93 (0x5d ). maxstack 2 // define the variable. locals Init ([0] float32 Val, [1] int32 I) il_0000: NOP il_0001: LDC. r4 0.69999999 // assign 0.69999999 to 0th variables. It is clearly defined as 0.7 il_0006: stloc.0 il_0007: LDC. i4.s 10/assign 10 to the first variable il_0009: stloc.1 // 0.7 il_000a: LDC of the double type. r8 0.69999999999999996 il_0013: ldloc.1 il_0014: Conv. r8 il_0015: Mul il_0016: Call float64 [mscorlib] system. math: floor (float64) il_001b: Call void [mscorlib] system. console: writeline (float64) il_0020: NOP il_0021: ldloc.0 il_0022: Call void [mscorlib] system. console: writeline (float32) il_0027: NOP // load Val il_0028: ldloc.0 // load I il_0029 from the stack: ldloc.1 // convert I to the float type il_002a: Conv. r4 // Val * I il_002b: Mul // convert the result after multiplication to the double type il_002c: Conv. r8 // call math. floor: il_002d: Call float64 [mscorlib] system. math: floor (float64) il_0032: Call void [mscorlib] system. console: writeline (float64) il_0037: NOP il_0038: ldloc.0 il_0039: Conv. r8 il_003a: Call void [mscorlib] system. console: writeline (float64) il_003f: NOP il_0040: ldloc.0 il_0041: ldloc.1 il_0042: Conv. r4 il_0043: Mul il_0044: Conv. r8 il_0045: Call void [mscorlib] system. console: writeline (float64) il_004a: NOP il_004b: ldloc.0 il_004c: Conv. r8 il_004d: ldloc.1 il_004e: Conv. r8 il_004f: Mul il_0050: Call void [mscorlib] system. console: writeline (float64) il_0055: NOP il_0056: Call string [mscorlib] system. console: Readline () il_005b: Pop il_005c: Ret} // end of method program: Main