Is there a way to traverse character by character or extract a single character from char* in C?
Consider the following code. Now which is the best way to get individual characters? Suggest me a method without using any string functions.
char *a = "STRING"; Another way:
char * i; for (i=a; *i; i++) { // i points successively to a[0], a[1], ... until a '\0' is observed. } 
i inside your for loop which you don't need to do with a[foo]. This could muddy the answer for a beginner.
a[i], there is always the addition a+i, where a is a pointer and i an integer. This is inferior to just i++ where i is a pointer if a[i] resp. *i is used multiple times inside the loop. But this is micro-optimization.
i. ++i could only be more efficient if "most cases" if most code is very feebly optimized, but closely considering the performance of unoptimized code is fairly futile. In C++ it's true that for user-defined types, the optimization is a little harder in general and sometimes actually impossible.*i is \0, for obvious reasons (\0 is the null byte, which is == 0 and evaluates to false in boolean contexts).Knowing the length of the char array, you can cycle through it with a for loop.
for (int i = 0; i < myStringLen; i++) { if (a[i] == someChar) //do something } Remember, a char * can be used as a C-Style string. And a string is just an array of characters, so you can just index it.
EDIT: Because I was asked on the comments, see section 5.3.2 of this link for details on arrays and pointers: http://publications.gbdirect.co.uk/c_book/chapter5/pointers.html
size_t i; for (i=0; a[i]; i++) { /* do something with a[i] */ } 
Like this.
char a1[] = "STRING"; const char * a2 = "STRING"; char * c; /* or "const char" for a2 */ for (c = aN; *c; ++c) { /* *c is the character */ } Here N can be 1 or 2. For a1 you can modify the characters, for a2 you cannot. Note that assigning a string literal to a char* is deprecated.
int i=0; while(a[i]!=0)/* or a[i]!='\0' */ { // do something to a[i] ++i; } EDIT:
You can also use strlen(a) to get the number of characters in a.
++i now though.