int main()
{
FILE *fa, *fb, *fc;
int i, j, k;
char str1[100], str2[100];
char tem;
if((fa = fopen("A.txt", "r")) == NULL)
{
exit(0);
}
fgets(str1, 99, fa);
fclose(fa);
if((fb = fopen("B.txt", "r")) == NULL)
{
exit(0);
}
fgets(str2, 99, fb);
fclose(fb);
strcat(str1, str2);
printf("%s\n", str1);
if((fc = fopen("C.txt", "w")) == NULL)
{
exit(0);
}
fputs(str1, fc);
fclose(fc);
return 0;
}