字符串处理函数集合

// strcpy.c
#include <syslib.h>
#include <string.h>
main()
{
    char *s="Golden Global View";
    char d[20];
    clrscr();
    strcpy(d,s);
    printf("%s",d);
    getchar();
    return 0;
}

 1 // strcat.c
 2 #include <syslib.h>
 3 #include <string.h>
 4 main()
 5 {
 6     char d[20]="Golden Global";
 7     char *s=" View";
 8     clrscr();
 9     strcat(d,s);
10     printf("%s",d);
11     getchar();
12     return 0;
13 }

// strlen.c
#include <syslib.h>
#include <string.h>
main()
{
    char *s="Golden Global View";
    clrscr();
    printf("%s has %d chars",s,strlen(s));
    getchar();
    return 0;
}

// strncat.c
#include <syslib.h>
#include <string.h>
main()
{
    char d[20]="Golden Global";
    char *s=" View WinIDE Library";
    clrscr();
    strncat(d,s,5);
    printf("%s",d);
    getchar();
    return 0;
}

 1 // strncpy.c
 2 #include <syslib.h>
 3 #include <string.h>
 4 main()
 5 {
 6     char *s="Golden Global View";
 7     char *d="Hello, GGV Programmers";
 8     char *p=strdup(s);
 9     clrscr();
10     textmode(0x00); // enable 6 lines mode
11     strncpy(d,s,strlen(s));
12     printf("%s\n",d);
13     strncpy(p,s,strlen(d));
14     printf("%s",p);
15     free(p);
16     getchar();
17     return 0;
18 }

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <alloc.h>
 4 int main(void)
 5 {
 6     char *string1 = "1234567890";
 7     char *string2 = "747DC8";
 8     int length;
 9     length = strcspn(string1, string2);
10     printf("Character where strings intersect is at position %dn", length);
11 return 0;
12 }

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <alloc.h>
 4 int main(void)
 5 {
 6     char *dup_str, *string = "abcde";
 7     dup_str = strdup(string);
 8     printf("%sn", dup_str);
 9     free(dup_str);
10     return 0;
11 }

#include <string.h>
#include <stdio.h>
int main(void)
{
    char *buf1 = "BBB", *buf2 = "bbb";
    int ptr;
    ptr = stricmp(buf2, buf1);
    if (ptr > 0)
    printf("buffer 2 is greater than buffer 1n");
    if (ptr < 0)
    printf("buffer 2 is less than buffer 1n");
    if (ptr == 0)
    printf("buffer 2 equals buffer 1n");
    return 0;
}

1 #include <stdio.h>
2 #include <errno.h>
3 int main(void)
4 {
5     char *buffer;
6     buffer = strerror(errno);
7     printf("Error: %sn", buffer);
8     return 0;
9 }

 1 #include <string.h>
 2 #include <stdio.h>
 3 int main(void)
 4 {
 5     char *buf1 = "BBB", *buf2 = "bbb";
 6     int ptr;
 7     ptr =strcmp(buf2, buf1);
 8     if (ptr > 0)
 9         printf("buffer 2 is greater than buffer 1n");
10     if (ptr < 0)
11         printf("buffer 2 is less than buffer 1n");
12     if (ptr == 0)
13         printf("buffer 2 equals buffer 1n");
14     return 0;
15 }

#include <string.h>
#include <stdio.h>
int main(void)
{
    char *buf1 = "BBBccc", *buf2 = "bbbccc";
    int ptr;
    ptr = strncmp(buf2,buf1,3);
    if (ptr > 0)
        printf("buffer 2 is greater than buffer 1n");
    if (ptr < 0)
        printf("buffer 2 is less than buffer 1n");
    if (ptr == 0)
        printf("buffer 2 equals buffer 1n");
    return 0;
}

 1 #include <string.h>
 2 #include <stdio.h>
 3 int main(void)
 4 {
 5     char *buf1 = "BBBccc", *buf2 = "bbbccc";
 6     int ptr;
 7     ptr =strnicmp(buf2, buf1, 3);
 8     if (ptr > 0)
 9         printf("buffer 2 is greater than buffer 1n");
10     if (ptr < 0)
11         printf("buffer 2 is less than buffer 1n");
12     if (ptr == 0)
13         printf("buffer 2 equals buffer 1n");
14     return 0;
15 }

#include <stdio.h>
#include <string.h>
int main(void)
{
    char letter = ‘x‘;
    printf("string beforestrnset: %sn", string);
    strnset(string, letter, 13);
    printf("string afterstrnset: %sn", string);
    return 0;
}

 1 #include <stdio.h>
 2 #include <string.h>
 3 int main(void)
 4 {
 5     char *string1 = "abcdefghijklmnopqrstuvwxyz";
 6     char *string2 = "onm";
 7     char *ptr;
 8     ptr = strpbrk(string1, string2);
 9     if (ptr)
10         printf("strpbrk found first character: %c\n", *ptr);
11     else
12         printf("strpbrk didn‘t find character in setn");
13     return 0;
14 }

 1 #include <string.h>
 2 #include <stdio.h>
 3 int main(void)
 4 {
 5     char string[15];
 6     char *ptr, c = ‘r‘;
 7     strcpy(string, "This is a string");
 8     ptr = strrchr(string, c);
 9     if (ptr)
10         printf("The character %c is at position: %dn", c, ptr-string);
11     else
12         printf("The character was not foundn");
13     return 0;
14 }

 1 #include <string.h>
 2 #include <stdio.h>
 3 int main(void)
 4 {
 5     char *forward = "string";
 6     printf("Before strrev(): %sn", forward);
 7     strrev(forward);
 8     printf("After strrev(): %sn", forward);
 9     return 0;
10 }

 1 #include <stdio.h>
 2 #include <string.h>
 3 int main(void)
 4 {
 5     char string[10] = "123456789";
 6     char symbol = ‘c‘;
 7     printf("Beforestrset(): %sn", string);
 8     strset(string, symbol);
 9     printf("Afterstrset(): %sn", string);
10     return 0;
11 }

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <alloc.h>
 4 int main(void)
 5 {
 6     char *string1 = "1234567890";
 7     char *string2 = "123DC8";
 8     int length;
 9     length = strspn(string1, string2);
10     printf("Character where strings differ is at position %dn", length);
11     return 0;
12 }

1 #include <stdio.h>
2 #include <string.h>
3 int main(void)
4 {
5     char *str1 = "Borland International", *str2 = "nation", *ptr;
6     ptr = strstr(str1, str2);
7     printf("The substring is: %sn", ptr);
8     return 0;
9 }

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 int main(void)
 4 {
 5     char input[80], *endptr;
 6     double value;
 7     printf("Enter a floating point number:");
 8     gets(input);
 9     value = strtod(input, &endptr);
10     printf("The string is %s the number is %lfn", input, value);
11     return 0;
12 }

#include <string.h>
#include <stdio.h>
int main(void)
{
    char input[16] = "abc,d";
    char *p;
    /* strtok places a NULL terminator
    in front of the token, if found */
    p = strtok(input, ",");
    if (p) printf("%sn", p);
    /* A second call to strtok using a NULL
    as the first parameter returns a pointer
    to the character following the token */
    p = strtok(NULL, ",");
    if (p) printf("%sn", p);
    return 0;
}

#include <stdlib.h>
#include <stdio.h>
int main(void)
{
    char *string = "87654321", *endptr;
    long lnumber;
    /* strtol converts string to long integer */
    lnumber = strtol(string, &endptr, 10);
    printf("string = %s long = %ldn", string, lnumber);
    return 0;
}

 1 #include <stdio.h>
 2 #include <string.h>
 3 int main(void)
 4 {
 5     char *string = "abcdefghijklmnopqrstuvwxyz", *ptr;
 6     /* converts string to upper case characters */
 7     ptr =strupr(string);
 8     printf("%sn", ptr);
 9     return 0;
10 }

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
char source[15] = "rFna koBlrna d";
char target[15];
int main(void)
{
    swab(source, target, strlen(source));
    printf("This is target: %sn", target);
    return 0;
}

 1 // isalpha.c
 2 #include <syslib.h>
 3 #include <ctype.h>
 4 #include <stdio.h>
 5 int main()
 6 {
 7     int c;
 8     clrscr(); // clear screen
 9     printf("Press a key");
10     for(;;)
11     {
12         c=getchar();
13         clrscr();
14         printf("%c: %s letter",c,isalpha(c)?"is":"not");
15     }
16     return 0; // just to avoid warnings by compiler
17 }