How can I pause my program inside a for(;;) loop? - c++

Question

I have a for loop inside my program that there is a call to espeak engin inside it:
The text is given by the other app and is different in every cycle of loop, and I am trying to get this text, pass it to espeak, it says the text, and the rest of the code will running(printing the given text for example).
But the problem is that, when espeak is talking, the rest of code doesn't wait till it ends the speaking, and I am looking for a way to pause the program till the espeak ends, then rest of the code will execute, but don't know how?
#include <string.h>
#include <malloc.h>
#include <espeak/speak_lib.h>
espeak_POSITION_TYPE position_type;
espeak_AUDIO_OUTPUT output;
char *path=NULL;
int Buflength = 1000, Options=0;
void* user_data;
t_espeak_callback *SynthCallback;
espeak_PARAMETER Parm;
char Voice[] = {"English"};
unsigned int Size,position=0, end_position=0, flags=espeakCHARS_AUTO, *unique_identifier;
espeak_init()
{
output = AUDIO_OUTPUT_PLAYBACK;
espeak_Initialize(output, Buflength, path, Options );
espeak_SetVoiceByName(Voice);
const char *langNativeString = "en";
espeak_VOICE voice = {0};
// memset(&voice, 0, sizeof(espeak_VOICE));
voice.languages = langNativeString;
voice.name = "US";
voice.variant = 2;
voice.gender = 1;
espeak_SetVoiceByProperties(&voice);
Size = strlen(text)+1;
}
int main()
{
for(;;)
{
...
espeak_Synth( text, Size, position, position_type, end_position, flags,unique_identifier, user_data );
espeak_Synchronize( );
// REST OF THE CODE...PRINTING THE WORLD THAT ESPEAK SAID FOR EXAMPLE
printf("\n %s \n", text);
...
}
}