Reversing a String in C
Two examples of reversing a string: one using malloc to allocate memory for a string and the other using only a single character space.
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char* reverseStr1( char* str )
{
char *ptr;
int len, i;
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len = strlen( str ); |
// Find length of string |
ptr = malloc( sizeof( char ) *( len+1 ) ); |
// Allocate memory for new string |
for( i = len-1; i >= 0; i-- )
{ |
// start at end of string and move back |
*( ptr+len-i-1 ) = *( str+i ); |
// put last letter into first position of new string |
} |
// then next in succesion etc. |
*( ptr+len ) = '\0'; |
// Add end of string character to end of new string |
return ptr;
}
void reverseStr2( char* str )
{
int i, j, len;
char tmp;
i = j = len = tmp = 0;
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len = strlen( str ); |
// Find length of string |
for ( i = 0, j = len-1; i <= j; i++, j-- )
{ |
// Start at end of string and move back
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tmp = str[ i ]; | // For the first iteration of the loop:-
// store first letter |
str[ i ] = str[ j ]; |
// put last letter of old string into first position of new |
str[ j ] = tmp;
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// put stored first letter into last position of new string
// then next in succesion etc. |
}
}
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(c) Compiled by B V Wood.
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