70 points to recruit C language experts, 9 questions, 3 programming, and the rest of the small questions (online, etc. )

1, %g is an output format selected by printf from %e, %f, which is considered meaningful to programmers. 123.56789 is useless by scientific counting, so it is output with %f, but only 6 significant digits are reserved when outputting.

2.%.7f means that the decimal part should be supplemented by 7 digits when outputting, so your topic is copied wrong, and you should output 13.00.

3.%6d indicates that when outputting an integer, the left space is filled with 6 digits, so the output: (space) (space)123 # #; % 14.8lf indicates that when floating-point numbers are output, the decimal part needs to be supplemented by 8 bits, the integer part needs to be supplemented by 14 bits, and spaces are added to the left, so the output is: (space) (space) (space)1.34550000 #.

4.I, J, k J and K are integers, scanf ("%d ",&; I)； When I read. Because. It will never appear in an integer, and scanf assigns 12 to the front. To I as the first integer, and then scanf ("%d ",&; J), scanf("%d ",& ampk), all reading. , and did not read the integer, so both failed, so the values of j and k did not change, or the initial value of 0.

5. In fact, if (x>0) y =1; Otherwise y = 0；; These two sentences only work, and the role of the first two sentences is obliterated by these two sentences. So x>0, y= 1, otherwise y=0.

6、! Is the negation operator! It is really fake! False is true, in C language, 0 means false, and non-zero value means true, so! 0 is 1! (nonzero value) =0.

7、

# include & ltstdio.h & gt

Invalid master (invalid)

{

Double t, s;

s = t = 1；

for(int I = 1； I & lt=50; i++)

{

t * = I；

s+= 1/t；

}

printf("%f\n "，s)；

}

8. This topic is completely meaningless. In reality, how old a person is, just subtract the year of birth from the current year. If you have to say your actual age, you just need to see if you have a birthday. It's y 1-y0 when it arrives, and y 1-y0- 1 when it doesn't arrive.

9. I really couldn't think of any good methods at that time. Let's assume that x is an integer and do it in the most troublesome way.

Switch (x)

{

Case 4: Case 3: Case 2: Case 1:

y = x； Break;

Case 0:

y = x- 1； Break;

Case 1: case 2: case 3: case 4: case 5:

Case 6: Case 7: Case 8: Case 9:

y = x+ 1； Break;

Default value:

Printf ("Error! \ n ")；

}