#include <stdio.h>

#include <conio.h>

#include <stdlib.h>

#include <string.h>

#include <iostream.h>

void nhapchuoi(char *a)

{

printf("Nhap chuoi ki tu: ");

gets(a);

}

void xuatchuoi(char *a)

{

printf("

CHuoi la: %s",a);

}

...............................

void daochuoi(char *a)

{

int n = strlen(a);

printf("

n = %d

",n);

int i = 0;

char c;

for ( i = 0;i < n/2 ; i++)

{

//printf("%c", a[i]);

c = a[i];

a[i] = a[n -i-1];

a[n -i-1] = c;

//printf("%c", a[i]);

//printf("%c",a[n-i +1]);

}

}

.................................

void xoa_kt(char *a)

{

int n = strlen(a);

int i =0;

int j;

do

{

if(a[i] == ' ')

{

for(j = i; j<n ; j++)

{

a[j] = a[j+1];

}

//free(a);

i = i -1;

n = n-1;

}

i = i +1;

}

while(i<n);

xuatchuoi(a);

}

................................

Loại bỏ khoảng trống thừa trong chuỗi

#include <stdio.h>

#include <string.h>

#include <conio.h>

#pragma warn -pia

char *trim(char *chuoi)

{

char *p;

while (p = strstr(chuoi, " "))

memmove(p, p+1, strlen(chuoi) - (p - chuoi));

if (chuoi[0] == ' ')

memmove(chuoi, chuoi+1, strlen(chuoi) - 1);

if (chuoi[strlen(chuoi)-1] == ' ')

chuoi[strlen(chuoi)-1] = 0;

return chuoi;

}

void main()

{

char chuoi[125];

printf("

Nhap chuoi mau : ");

textattr(0x1e);

gets(chuoi);

trim(chuoi);

printf("

Chuoi sau khi da trim : ");

textattr(0x1e);

cputs(chuoi);

getch();

}

........................................

Đếm ký tự trong 1 tập tin

#include <stdio.h>

#include <ctype.h>

void main()

{

FILE *fp;

char sf[50], c;

long count = 0;

printf("

Nhap vao ten tap tin : ");

scanf("%s", sf);

if ((fp = fopen(sf, "r")) == NULL)

fprintf(stderr, "

Khong the mo tap tin %s", sf);

else

{

while ((c = fgetc(fp)) != EOF)

if (isalpha©)

count++;

printf("

So ky tu trong %s la %ld", sf, count);

}

getch();

}