Increase or subtract 1 from a large number -- put both numbers before and after the inversion to align the digit

# Include <stdio. h> // store the read data to num [1] ~ In num [X], num [0] indicates the length of the stored data. Void read (INT num []) {int I; char ch; for (I = 0; I <500; I ++) num [I] = 0; I = 1; while (CH = getchar ())! = '\ N') {num [I] = CH-'0'; I ++; num [0] ++ ;}} // flip the number in data num [] to calculate void Rev (INT num []) {int I, T; for (I = 1; I <= num [0]/2; I ++) {T = num [I]; num [I] = num [num [0] + 1-I]; num [num [0] + 1-I] = T;} void print (INT num []) {char character [11] = {"0123456789 -"}; // character [N] indicates the character form of number n. Character [10] = '-' is used to output the negative number in the subtraction result. Int I; for (I = 1; I <= num [0]; I ++) printf ("% C", character [num [I]); printf ("\ n");} // Add the values of a [] and B [] and store them in sum. Void add (INT sum [], int A [], int B []) {// flag is the carry flag. Int I, flag = 0; Rev (a); Rev (B); for (I = 1; I <= A [0] | I <= B [0]; I ++) sum [I] = A [I] + B [I]; if (a [0]> B [0]) sum [0] = A [0]; else sum [0] = B [0]; for (I = 1; I <= sum [0]; I ++) {sum [I] + = flag; If (sum [I]> 9) {sum [I] = sum [I] % 10; flag = 1 ;} else flag = 0;} if (1 = Flag) {sum [0] + = 1; sum [I] = 1;} Rev (SUM); Rev (); // After the addition operation, flip a and B back. Rev (B);} void sub (INT rst [], int A [], int B []) {int I; int flag = 0; // flag is a flag. Rev (a); Rev (B); for (I = 1; I <= A [0] | I <= B [0]; I ++) RST [I] = A [I]-B [I]; if (a [0]> B [0]) rst [0] = A [0]; else rst [0] = B [0]; for (I = 1; I <= rst [0]; I ++) {rst [I] + = flag; if (RST [I] <0) {flag =-1; rst [I] + = 10;} else flag = 0;} If (-1 = Flag) {// at this time, flag =-1 indicates a-B <0, so it is converted to B-. You need to first flip A and B to the original data Rev (a); Rev (B); sub (RST, B, A); // After the sub operation, A, B, the RST is in the normal format. You need to flip it and add a negative number. Rev (RST); Rev (a); Rev (B); // Add the '-' rst [0] ++ to the highest bit of the result; RST [rst [0] = 10; // If a value is 10, this bit is "-";} Rev (RST); Rev (); rev (B);} int main () {int A [500], B [500], he [500], Cha [500]; printf ("input: "); read (A); printf (" input B: "); read (B); add (HE, a, B); sub (CHA, A, B ); print (HE); print (CHA); Return 0 ;}