C + + basic problem--float type output in integer format

1 intMain ()2 {3     floatA =765;4a++;5printf"%d\n", a);6System"Pause");7     return 0;8 }9 //why would the output be 0? Ten The explanations are as follows: OneWhen you are in printf,floatis automatically converted to double type, from 32 bits to 64 bits. %d output is the lowest of 32 bits.  A The computer is a small terminal mode, so when saving 765, it is the following format - bottom of the stack (high-byte) ....... Stack top (low byte) - 765                           0000 the The following question is extended - intMain () { -intAfloatb,c; -scanf"%2d%3f%4f",&a,&b,&c); +printf"\na=%d,b=%d,c=%f\n", a,b,c); - } +If you enter 9876543210l from the keyboard at runtime, the output from the above program under the GCC compiler is a=98, b=0, c=0.000000 A parsing: at when printf, float is automatically converted to double type, so variable b and variable C go from 32 to 64 bits; -B is in%d in the format of the output, so the output is the lowest 32 bits.  -The computer is a small-end mode-High-byte high address, low-byte low address - printf presses the stack in order from right to left, thus first pressing C, then B, then A; - bottom of the stack (high-byte) ....... Stack top (low byte) - 4321     0000      765     0000         98 in 4 bytes 4 bytes 4 bytes 4 bytes 4 bytes - The output starts at low byte, to first output A, four bytes, i.e. 98 + then output B, four bytes, or 0 - then output C, eight bytes, is the normal way to print, will read eight bytes at a time, exactly the first four bytes are all 0. Because of the way floating-point numbers are stored, theThe 64-bit contains 1 sign bits, 11 orders, 52 Mantissa, order 0, indicating-1023+1023=0, denoted by an exponent:1.#*2^-1023, * ' # ' represents the mantissa. The Mantissa is 000 ... The number behind is small, so this floating point is very small. This problem can be said to be the output mode of B influence $C, if B is output with%f, then B and C will display correctly

C + + basic problem--float type output in integer format