动态内存分配,字符串长度,字符串比较,字符串复制

动态内存分配

#include

#include

int main(void)

{

int number;

int *a;

int i;

printf("输入数量：");

scanf("%d",&number);

// int a[NUMBER];

a = (int*)malloc(number*sizeof(int));

for(i=0;i

{

scanf("%d",&a[i]);

}

for (i=number-1;i>=0;i--)

{

printf("%d",a[i]);

}

free(a);

return 0;

}

#include

int main(int argc ,char const *argv[]) {

int i;

for ( i=0;i

{

printf("%d:%s\n",i,argv[i]);

}

return 0;

}

字符串长度

{{strlen(s1)}}

#include

#include

int mylen (const char* s)

{

int idx = 0;

while (s[idx]!='\0') {

idx++;

}

return idx;

}

int main(int argc , char const *argv[])

{

char line[] = "hello";

printf("strlen=%lu\n",mylen(line));

printf("sizeof=%lu\n",sizeof(line));

return 0;

}

字符串比较

{{strcmp(s1,s2)}}

#include

#include

int mycmp(const char* s1,const char *s2)

{

while (*s1==*s2&&*s1!='\0')

{

s1++;

s2++;

}

return *s1-*s2;

}

int main(int argc ,char const *argv[])

{

char s1[]="abc";

char s2[]="abc";

printf("%d\n",mycmp(s1,s2));

printf("%d\n",'a'-'A');

return 0;

}

字符串复制

char *strcpy(char *restrict dst ,const char *restrictsrc);

char* strstr(const char *s1, const char *s2); char *strcasestr(const char *s1,constchar *s2);

#include

#include

#include

int main( int argc ,char const *argv[])

{

char s[]="hello";

// scanf("%s",s);

char *p=strchr(s,'l');

char c=*p;

*p='\0';

char *t =(char*)malloc(strlen(s)+1);

strcpy(t,s);

printf("%s\n",t);

free(t);

return 0;

}