How to Use scanf statements to input multiple values in C Language

Today, using community variables to write a small program requirement: There are several personnel data, including students and teachers. Student Data includes name, number, gender, occupation, and class. Instructor data includes name, number, gender, occupation, and position. The same table must be used for processing. After compilation, run the program and find that the output has a problem. The problem occurs in the scanf statement through debugging. The original scanf statement is scanf ("% d % S % C ", & person [I]. num, & person [I]. name, & person [I]. sex, & person [I]. job. the job value is & person [I]. sex overwrites M. 1. Try to add a space in the middle of % d % S % C, and the output result returns normally. 2. You want to add a comma between % d % S % C, and the output result is still incorrect. However, when writing a simple scanf function, both methods 1 and 2 can output normal results. I wonder if this problem is caused by the use of struct variables or community variables. Do you have any special requirements on the input/output format when using struct or community variables? Please help me. Source code (corrected): # include <stdio. h> struct student {int num; char name [20]; char sex; char job; Union {int CLAS; char position [20];} category;} person [2]; int main () {int I; for (I = 0; I <2; I ++) {printf ("Please enter the date of person: \ n "); scanf ("% d % S % C", & person [I]. num, & person [I]. name, & person [I]. sex, & person [I]. job); If (person [I]. job ='s) {printf ("Enter the student's class: \ n"); scanf ("% d", & person [I]. category. CLAS);} else if (person [I]. job = 'T') {printf ("Enter the instructor's position: \ n"); scanf ("% s", & person [I]. category. position);} elseprintf ("incorrect input job type");} printf ("\ n"); for (I = 0; I <2; I ++) {If (person [I]. job ='s) printf ("the student's information is as follows: % 6D % 10 S % 4C % 4C % 10d \ n", person [I]. num, person [I]. name, person [I]. sex, person [I]. job, person [I]. category. CLAS); elseprintf ("the instructor information is as follows: % 6D % 10 S % 4C % 4C % 10s \ n", person [I]. num, person [I]. name, person [I]. sex, person [I]. job, person [I]. category. position);} return 0 ;}

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Satisfactory answer

There is a very serious error. You enter two scanf characters in the character array ("% d % S % C", & person [I]. num, & person [I]. name, & person [I]. sex, & person [I]. job); scanf ("% s", & person [I]. category. position); remove the & symbol before the character array input in the two rows. The input to the character array is the address, do not add & change to scanf ("% d % S % C", & person [I]. num, person [I]. name, & person [I]. sex, & person [I]. job); scanf ("% s", person [I]. category. position); there are no other errors when you remember to input them, the values are separated by a space.

Question

Person [I]. Num is a member of the struct array. To assign values to members, add? I wrote the statement as follows but the output result is correct. I wonder if there are any internal risks? I just started to learn the C language. I hope you can help me introduce it.

Answer

When using the scanf () function, the essence is that you give scanf an address. This function will put the data in the input buffer at the specified address, such as int, Char, double, long, float are the basic types. When allocating space, you only need to give them a space. Therefore, when using scanf () for input, you need to add the & get address symbol, in order to assign values to them. However, char *, char [], these are the first addresses of a region, and they are the addresses themselves. Therefore, when scanf is used, do not add them, you do not need to add only person [I] in the input. name, person [I]. category. position, and the rest are basic types. Therefore, you must add

Question

I understand, as I previously wrote, there may be no problem during running, but the person [I] stored in the memory. category. position data is only the first character of the input string, right? This debugging process can be seen (the debugging program just learned today ).