VC source code: strcmp function writing: # include <stdio. h> # include <string. h> int strcmp1 (char * a, char * B) {for (; * A = * B; A ++, B ++) if (*! = '\ 0') return 0; return * A-* B;} Main () {int L; char a [10] = {"DB "}; char B [10] = {"CB"}; L = strcmp1 (a, B); printf ("% d \ n", L );}
Strcat function Syntax: # include <stdio. h> # include <string. h> char * strcat1 (char * DST, char * SRC) {char * CP = DST; while (* CP) CP ++; /* Find end of DST */while (* CP ++ = * SRC ++);/* Copy SRC to end of DST */Return (DST ); /* return DST */} Main () {char a [10] = {"wangefng"}; char B [10] = {"junzi"}; strcat1 (, b); puts (a);} strcpy function Syntax: # include <stdio. h> # include <string. h> char * strcpy1 (char * To, char * From) {char * P = to; while (* to + + = * From ++); Return P;} Main () {char a [10] = {"wangefng"}; char B [10] = {"junzi "}; strcpy1 (a, B); puts (a);} strcat Function Array Implementation: # include <stdio. h> void strcat1 (char s [], char T []) {Int J = 0, I = 0; while (s [I]! = '\ 0') // determines whether it is the end of string s I ++; while (S [I] = T [J])! = '\ 0') I ++, J ++;} Main () // main function, function used to test the strcat function {char s [20] = "I love"; // The character array S should be defined with sufficient length, to load the connected string char T [] = "you"; strcat1 (S, T); // call the string connection function printf ("the length of the connected string is: % s \ n ", S );
} Strcat function pointer implementation: # include <stdio. h> char * strcat1 (char * s, char * t) {While (* s) // judge whether it is the end of string s ++; while (* s ++ = * t ++) // copy the string in T to the end of S; return s;} Main () // main function, function used to test the strcat function {char a [20] = "I love"; // character array S should be defined with sufficient length, to load the connected string char B [5] = "you"; strcat1 (a, B); // call the string connection function printf ("the length of the connected string is: % s \ n ", a) ;}# include <stdio. h> void connect (char str1 [], char str2 []) {int I, j; I = strlen (str1); For (j = 0; str2 [J]! = '\ 0'; j ++) str1 [I + J] = str2 [J]; str1 [I + J] =' \ 0';} Main () {char str1 [200], str2 [100]; printf ("Please input the first string: \ n"); gets (str1); printf ("Please input the second string: \ n "); gets (str2); Connect (str1, str2); printf (" after CONNECT: \ n "); puts (str1 );}
Strlen function pointer Syntax: # include <stdio. h> # include <string. h> char strlen1 (char * s) {int I = 0; while (* s ++) ++ I; return I;} Main () {char s [10] = "Iloveyou"; printf ("String Length: % d \ n", strlen1 (s ));}
You can also use the For Loop: Char strlen1 (char * s) {int N; For (n = 0; * s! = "\ 0"; s ++) n ++; return n ;}} strlen function syntax # include <stdio. h> int strlen1 (char * s) {int n = 0; while (s [N]! = '\ 0') + + N; return N;} Main () {char s [10] = "Iloveyou"; printf ("% d \ n ", strlen1 (s ));
2. Write a function int fun (char * P) to judge whether a string is a return text. If it is 1, it is not 0. If an error is returned, it is-1.
Int fun (char * P) {int I = 0, Len = 0, flag = 0; while (* P )! = '\ 0') {P ++; Len ++;} If (LEN = 0) return flag =-1; P = p-len; for (I = 0; I <= Len/2; I ++) {If (P [I]! = P [len-1-i]) return flag = 0;} return flag = 1 ;}}
Int strcmp (const char * str1, const char * str2) {int Len = 0; while (* str1 & * str2 & (* str1 = * str2 )) {str1 ++; str2 ++;
}
Return * str1-* str2;
}
How to Write strcpy, strcmp, strcat, and strlen Functions
